Monday, July 9, 2018

The odd seed baskets of carrots

Flowers of the carrot, Daucus carota, are borne in a flat-topped
inflorescence called a compound umbel.  Ignore the
foliage in this photo, as it belongs to a neighboring potato plant.

Most people don't notice the elegant inflorescences of the carrot plant (Daucus carota).  If you do, it usually means you've waited too long to harvest the edible, orange taproots.  If you have seen them, you might have noted the resemblance to Queen Anne's Lace, which is in fact a wild relative of the cultivated carrot. 

The individual white flowers are borne in small, flat-topped clusters called umbels, for their resemblance to little umbrellas.  The umbels, moreover, are grouped into a more compound structure, creating a large, flat-topped display for the tiny insects that will feed on the flowers and disperse their pollen.  The carrot family, Apiaceae, used to be called the Umbelliferae, after this characteristic inflorescence structure.  Celery, coriander, celantro, parsley, dill, fennel, and a host of other plants useful for nutrition and seasoning, belong also to this family.

Even fewer people have noticed the strange contortions these inflorescences undergo during their development and the maturation of their seeds.  As the young flowers begin to form, they are hidden and protected within the in-turned inflorescence branches and a series of spiky bracts.

As the flowers mature, the branches of the inflorescence expand and bend outwards to form the compound, flat-topped blooming structure.

The surprise comes as the flowers wither and their ovaries mature into the tiny, one-seeded fruits, that we superficially take for bare seeds.  The fruits of the  carrot and other members of the Apiaceae (sunk by some into the Araliaceae) are technically schizocarps, as they consist of two single-seeded units that split apart as they mature.  The fruit wall is thin, and dries into a hard outer layer on the seed, and so is unnoticed. 

As this ripening process proceeds, the branches of the inflorescence bend inwards again, bringing the fruits inside of  what is now a basket-like structure.  It is likely that this phenomenon is an adaptation for protecting the fruits from herbivores as they ripen, but I've not been able to find any literature to verify this.  The basket may also serve as a giant salt-shaker like structure that sways back and forth in the wind, helping fling the seeds away from the parent plant.  A similar structure has been noticed in the related genus, Conopodium, and is likely to be found in other members of the family.

As the young flowers develop, they are protected within the in-rolled
branches of the inflorescence.

As the ovaries of the flowers develop into the dry fruits known as schizocarps,
they are drawn inside of a basket-like structure, by the inward curving
 inflorescence branches.


Sunday, May 20, 2018

Are palms giant herbs?

The largest inflorescence in the world 
is that of a palm, Corypha
umbraculifera, which like the well-
known Century Plants in the New
World, dies after its massive
flowering.  The inflorescence
is said to contain approximately 
24 million flowers. 
Photo courtesy Scott Zona.

The  Palm Family (Arecaceae) includes some of the largest monocots in the world, and one could argue, the largest perennial herbs.

To call a massive palm tree an herb may seem like a strange statement, since it has a sturdy upright stem, and may live for 100 years or more. Palm trunks may be a meter or more in thickness (Roystonea or Jubaea), and they hold the records for the largest inflorescences (Corypha umbraculifera), the largest seeds (Lodoicea maldivica) and the largest leaves (Raphia regalis) in the plant kingdom.

The largest seed in the world, weighing
up to 55 pounds, is that of Lodoicea maldivica,
from the Seychelles Islands.  The large
seeds are thought to be an adaptation
for survival of seedlings in a thick forest
 with nutrient- poor soil. Posted on
Wikipedia, Creative Commons license.

Members of the genus Raphia in Africa have the largest leaves of any plant. Pictured is R. australis, which is truly huge,
but a camera-shy relative, R. regalis, has the largest leaves, measured at over 25 meters in length.
Photo posted on Wikipedia, Creative Commons  License.
So is a palm a herb? The traditional definition of a herbaceous plant (or simply herb, in a botanical rather than culinary sense) is that it lacks permanent, above-ground woody stems, though they may have woody underground parts. Tulips and dahlias are examples of perennial herbs, while pansies and marigolds are examples of annual herbs. The alternate category is woody perennials, which include trees, shrubs and lianas.  There are, in fact, some dwarf palms that do not produce upright stems.  They would clearly be perennial herbs.  But what about larger palms?

The  vegetation of herbaceous plants is produced entirely through primary growth, in which all tissues arise from the apical meristems, or buds, at the tips of the stems. In contrast, woody plants exhibit secondary growth both above and below ground.  It is important to note that wood is the production of concentric layers of secondary xylem.

Are bamboos, perennial herbs or trees? Photo by Alain Van den Hende,
posted on Wikipedia, Creative Commons License.
Tropical plants, and tropical monocots in particular, severely strain the distinction between those two categories. First of all, no monocot, even a palm "tree," has true woody tissues. Their stems, no matter how thick or dense, are produced entirely through primary growth, and are strengthened by dense masses of fibers, rather than by layers of secondary xylem.  For that reason alone, all monocots could be considered herbaceous.

Many botanists would consider that too picky, and would use the term "woody" in a broader sense to refer to the dense wood-like tissues of palms.  And there are a few monocots, such as the dragon trees, giant aloes and some dracaenas, that have a specialized form of secondary growth, but such growth adds only layers of fibers and vascular bundles, not layers of secondary xylem.

Even if we accept that palms and other giant monocots are trees, there are still many gray areas where one is not quite sure where herbaceous perennials end and trees begin, and so there is value in pointing out the distinction between the very different ways that monocots and dicots form tree-like growth forms (see The invention and reinvention of trees).

Monocots abandoned the ability to form true wood as their ancestors adapted to a growth form based on rhizomes, with leaves that elongate from the base, and short-lived upright reproductive shoots (see How the grass leaf got its stripes).  Leaves of monocots, which can  be relatively large, are heavily dependent on bundles of fibers for support against both gravity and wind, as well as sometimes for protection against herbivores.  As they spread to a wide variety of habitats, some monocots got larger and developed upright stems with increased density of supporting fibers.  Important commercial fibers come from a variety of monocots, including Manila hemp (from a type of banana), sisal (from a species of Agave), and New Zealand hemp (from Phormium).  Fiber can also be teased our of bamboo stems and the leaves, stems, and fruits of many palms. 

Tropical monocots tend to be evergreen, another way they differ from temperate herbs.  Banana plants, which are tree-like, but clearly herbaceous, remain above ground for several years.  Others, such as agaves, aloes, and birds-of-paradise have permanent tufts or rosettes of above-ground foliage, typically arising from underground rhizomes.  No one would confuse such plants with woody shrubs, and these must be considered  perennial herbs.   Other monocots, including many grasses (e.g. canes) have upright stems that are reinforced with fibers and may last for several years. Bamboos are giant grasses with sturdy upright stems that live for many years (see The grasses that would be trees).   Should they be called herbs or woody plants?  Neither, actually.

The whole point of this long diatribe is to once again to point out how different monocots are from other vascular plants.  Their growth forms cannot be classified in the same terms as dicots.  They have mimicked the forms of many other kinds of plants (e.g. palms vs cycads), but with very different patterns of growth and tissues. Some of the elaborate classifications of the past (try googling: "plant growth forms") included special categories for palms and bamboos, but many did not.  In my opinion, the term "woody" should not be used for any monocot.  We can substitute the word "fibrous," which will be much more accurate and informative.  Many tropical and xeric monocots can be referred to as evergreen perennial herbs.  That would cover agaves, aloes, yuccas, and birds-of-paradise, as well as smaller palms.  Tree-like monocots, such as coconut palms, bamboos, screw-pines, Joshua trees, and dragon trees, might be called "fibrous arborescent perennials."  

Wednesday, March 7, 2018

Mosses of Central Florida 52. Fontinalis sullivantii

Fontinalis sullivantii Lindberg (Fontinalaceae) is a straggling moss often found in water, but also on soil or tree bases in moist areas.  Leaves are spread primarily on two sides of the stem. Note all photos are of other species, provided to illustrate the general characteristics of the genus.

Fontinalis antipyretica, showing aquatic habitat.
Photo by Bernd Haynold, Creative Commons license,
posted on Wikimedia Commons
The stiff leaves lack a midrib, and the cells are worm-like, but plump, and densely filled with chloroplasts. A few cells at the base of the leaf are larger, more squarish, and clear.

Spore capsules appear along the stem and are nestled within a cluster of specialized leaves, lacking an elongate stalk.
The flattened leafy shoots of Fontinalis sullivantii.  Photo by
Kurt Stuber, Creative Commons license, posted on Wikimedia
The leaf tip of Fontinalis squamosa, showing the curvy,
worm-like cells filled with chloroplasts. 
Photo by Hermann Schachner, public domain, posted on
Wikimedia Commons

This species occurs throughout eastern U.S. and northern Europe.
It is found in northern Florida down to Hillsborough, Polk and Osceola Counties, though it has been sparsely collected.

Fontinalis may be confused with other aquatic mosses in Florida, but is distinguished from them by its lack of a midrib, the elongate, worm-like cells with thick walls, and the spore capsules that remain nestled within clusters of bract-like leaves.

Two other species have been collected sparsely in northern Florida: Fontinalis novae-anglae from the central Panhandle and possibly Orange County, and F. sphagnifolia, from central north Florida, with unconfirmed reports from Hillsborough and Polk Counties.  They differ in small, technical details.
The base of a leaf of Fontinalis antipyretica, showing larger,
clear, basal cells, captured nicely by Hermann Schachner, public
domain, posted on Wikimedia Commons.

Tuesday, March 6, 2018

Mosses of Central Florida 51. Leucodon julaceus

Leucodon julaceus (Hedwig) Sullivant (Leucodontaceae) forms colonies of erect leafy shoots arising from a branching stem system on tree trunks, logs, rock, and soil.
Photo by Scott Schuette, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.

Leaves are short and scale-like, with inrolled edges, evenly distributed around the stem, and  lack midribs. Leaf cells are roundish-angular and largely smooth, but with some papillae on cells near the tip. When dry, the leaves press against the stem, resembling a tiny juniper twig.

Spore capsules are erect and egg-shaped, on short stalks arising from among specialized long, sword-shaped bracts, usually near the tips of the leafy shoots.

This species is found throughout the eastern U.S. and southern Ontario, as well as in Mexico and the West Indies.   It is found in northern Florida south to Hillsborough and Manatee counties.

It is somewhat similar to Schwetschkiopsis fabronia, but the latter is confined more to the bases of trees, and the leaves are "bumpy" throughout due to the translucent cell wall projections at the ends of cells.  Clasmatodon parvulus and Papillaria nigrescens are also similar but their leaves have distinct midribs.
Photo by Gerritt Davidse, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.

Thursday, March 1, 2018

Mosses of Central Florida 50. Cyrto-hypnum minutulum

Cyrto-hypnum minutulum (Hedwig) W. R. Buck & H. A. Crum (Thuidiaceae)
is a creeping, freely branching moss found on rotting logs, the bases of trees, and rocks.
A dried specimen identified as Cyrto-hypnum minutulum in
USF Herbarium (Griepenburg s.n., 4 Apr 1970, Highland
Hammock State Park)

The leaves are scale-like, with small roundish to squarish cells with multiple papillae on both sides.  As in other members of the Thuidiaceae, leaves on the main stem are larger than on the branches.  The midrib extends 2/3 to 3/4 of the leaf length. Spore capsules are asymmetrical and bent to the side.

The related genus Thuidium differs in that papillae are found only on the lower surface, and there is usually only one per cell.

This species is found throughout state but lacking in the southern Atlantic counties.  It is also found throughout eastern N. America, Europe, and south into South America. 

Also found in Florida, but very limited in distribution and distinguished on minor characteristics are:
C. involvens, southern Florida north to Volusia County, but with major gaps.
C. pygmaeum, 2 records: Jackson and Manatee counties
C. schistocalyx : Highlands, Miami-Dade counties

The species has previously been known as Hypnum minutulum or Thuidium minutulum.

Wednesday, February 28, 2018

Mosses of Central Florida 49. Stereophyllum radiculosum

The flat, dried leaves of  Stereophyllum radiculosum have a
conspicuously bulging midrib.
Photo by Juan David Parra, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.
Stereophyllum radiculosum (Hooker) Mitten (Stereophyllaceae) forms thin, flat mats on the base of trees, exposed roots, stumps, logs, and limestone,  The distinctive flat leaves are attached uniformly around the stem (not flattened in a plane), elliptic-ovate in shape, and somewhat contorted when dry. The midrib is strong and markedly bulging, but does not reach the tip.  The leaf cells are small, roundish, and contains a single papillum (translucent bump). Spore capsules are erect to somewhat leaning,  asymmetrically egg-shaped, and arise from the bases of the leafy shoot on relatively short stalks (0.6-1.2 mm).

The leaning, egg-shaped spore capsule of Stereophyllum.
Photo by Juan David Parra, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.
This species is widespread in the tropics; found in the U.S. only in Alabama, Texas, and Florida, where it occurs in the southern part of the state as far north as Citrus, Volusia, and Alachua counties.

Most other creeping species found on tree bases have somewhat flattened shoots, with leaves mainly on two sides of the stem, and capsules strongly bent to the side (Isopterygium or Haplocladium) or symmetrical and upright (Sematophyllum, Entodon).

Monday, February 26, 2018

Mosses of Central Florida 48. Schlotheimia rugifolia

The distinctive brownish shoots of  Schlotheimia rugifolia.
Photo by Juan David Parra, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.

Schlotheimia rugifolia (Hooker) Schwagrichen (Orthotrichaceae) forms distinctive reddish-brown mats on logs, tree trunks, and branches.  The leafy shoots are more or less erect (extending away from attached base).  The flat leaves twist spirally around the stem when dry.

The narrow-ovoid capsules are usually erect, but bent in this
dry specimen. Photo by Juan David Parra copyright MBG,
posted on Tropicos,  available under a Creative Commons

The leaves  of this species are elliptic, with short point at tip and have a slight rumpled (rugose) appearance. The midrib is strong, extending through to the short point.  Leaf cells are small, roundish, and smooth.  The spore capsules are erect and narrow-ovate in shape. They arise from the tips of the leafy shoots on elongate stalks,
Schlotheimia rugifolia  is found throughout the southeastern U.S. as far north as Virginia and Tennessee, and extensively in the New World tropics.  In Florida, it has been collected throughout the state but with gaps.  In particular, it has not been collected in any of the Atlantic coastal counties between Volusia and Miami-Dade.

This is one of the relatively few mosses found in Florida that occur relatively high on the trunks and branches of trees.  The dark, reddish brown coloring, the distinctive spiral twisting of the dried leaves and the longer capsule stalks will distinguish it from others, such as SematophyllumCryphaea, and Forsstroemia, in this habitat.


Tuesday, February 13, 2018

Mosses of Central Florida 47. Aulocomnium palustre

Aulacomnium palustre (Hedwig) Schwagrichen (Aulacomniaceae) forms tufted colonies of upright leafy shoots on wet soil, marshes, swamps, and sometimes rocks.  It employs asexual propagation via small, modified, bullet-shaped or spear-point leaves clustered at the tips of elongate stems.

The upright shoots of Aulacomnium palustre form loose tufts
on wet soil. Photo by Robert A. Klips.

The leaves are elongate, with a prominent midrib, and gradually come to a point.  Leaf cells are small, roundish and papillose.  Spore capsules are bent to the side, and distinctly grooved, but are not commonly seen in our area, as asexual propagation is abundant.

A single tapered leaf of Aulacomnium palustre, showing
the prominent midrib and tiny, rounded cells.
Photo courtesy Western New Mexico Herbarium,
from the Gila Wilderness.
This species is found in every state and province of North America and throughout the northern hemisphere.  In Florida it has been collected in scattered counties in the northern half of the state, as far south as Polk County.

Wednesday, February 7, 2018

Mosses of Central florida 46. The genus Leskea

Leskea gracilescens growing on the side of a tree.  Photo by
Robert A Klips
Three of the four species of  Leskea found in North America have been reported from Florida: Leskea australis Sharp,  L. gracilescens Hedwig, and L. obscura Hedwig.   These are creeping, irregularly branched, mat-forming mosses, often with a reddish coloration, found on the bases or lower trunks of hardwoods and cypress trees, or on decaying logs. 
A leaf of Leskea gracilescens, showing the small roundish
cells with papillae (translucent light spots).  Photo by Kalman
Strauss, posted in the Consortium of North American
Bryophyte Herbaria database.
Leaves are ovate and pointed, with midribs that usually end before the tip.  Leaf cells are small, roundish, and papillose, and the spore capsules are erect and more-or-less symmetrical.

Only Leskea australis is known from central Florida.  It has been found throughout the state, but has not been reported from the extreme south, the western panhandle or the Atlantic coastal counties. Elsewhere, it is found throughout the southeastern U.S.
A leafy shoot of Leskea gracilescens with an inset of the
papillose leaf cells.  Photo by Robert A.Klips

The erect, symmetrical spore capsules of Leskea gracilescens.
Photo by Kalman Strauss.

L. gracilescens and L. obscura are both widely distributed in eastern North America, live in the same habitats as L. australis, and differ in minor ways. L. grascilescens has been reported from several counties in North Florida, elsewhere throughout eastern North America, and L. obscura only from Leon County.

Our Leskea species are similar to Haplocladium microphyllum, also in the Leskeaceae, but in Haplocladium the spore capsules are bent distincly to the side, and the leaf tips more drawn out into a narrow point.  H. microphyllum is also more likely found in soil, rocks or damp wood than on tree trunks. 

Tuesday, February 6, 2018

Pond edges, liverworts, and the earliest land plants

.The edge of a drying pond would hardly seem like a hospitable place for plant life.  During the wet season it is submerged, and during the dry season it can be completely dried out.  Yet for the few months when the shoreline is retreating, during winter and spring in Florida, the sandy soil between high and low water marks remains moist, and supports a variety of small, but quick-growing plants that complete their life cycles before being inundated again.
Some green plants can be seen along this drying pond edge, but
the most interesting residents can only be seen close-up.

I have previously reported on some ephemeral inhabitants of such pond edges, including the sundew, Drosera capillaris, and several mosses, including Rosulabryum capillarePhyscomitrium collenchymum, and some species of Micromitrium.  I expect to report on several other mosses with similar habits in the coming months.
Recently, I was out walking in my neighborhood, and decided to revisit the same pond edge where I had collected Physcomitrium collenchymum in late March a couple of years ago. Now, in late January, I was quite surprised to find two completely different bryophytes,  Riccia cavernosa, and a species of Sphaerocarpos - both liverworts - but no sign of the Physcomitrium.  I shall have to pay attention over the next several months, to see if there is a succession of different species that might include later appearances of a  moss or two.

Riccia forms a flat, forking thallus, while Sphaerocarpos takes the form of a rounded mound of upright shoots.
Riccia cavernosa is a thallose liverwort, meaning its body is in the form of a flattened, forking ribbon. Riccia species tend to spread outward from a central point, forming a round disk, at least when young, One can see here that the thallus is heavily pitted, giving it a spongy texture.

Sphaerocarpos species form cushions of odd egg-shaped shoots.
.Finding these liverworts got me to thinking again about the very first land plants, which  most likely lived in a similar habitat, and were similar in growth forms to modern thallose liverwort like Riccia.  Phylogenetic studies indicate that the closest living relatives of land plants are in the green algal genus Coleochaete, which has a similar flat, disk-like growth form.  So it is easy to see an ancient transition from one to the other.

The green alga, Coleochaete, grows as
a flat sheet of tissue (A,B) that expands
outward from its center. The roundish
bodies are zygotes, that will eventually
undergo meiosis to produce zoospores (C).
from Essig 2015, after Haupt.
To be sure, some major adaptive innovations took place as green algae moved onto land, especially in their mode of reproduction. Coleochaete, like other green algae, produces zoospores through meiosis of the zygote, while all bryophytes have a diploid sporophyte generation that produces non-motile, dessication-resistant spores through meiosis of cells within a spore chamber or capsule.

[several interesting copyrighted photos of Coleochaete species can be seen at The Vine Tendril , and The Algal Web.

Also to be sure, Riccia is a modern liverwort genus, and I don't suggest that the first land plant were members of that genus that have been sitting around unchanged for 400 million years.  Most likely the ancestors of Riccia readapted to this habitat, as many others have over the ages, including the Sphaerocarpos, various mosses, and certainly the Drosera.

Part of that readaptation, is a shift back to the means of spore dispersal most likely practiced by the first land plants. In most bryophytes, the spore capsule is elevated by a stalk to facilitate wind-dispersal. The spore chamber of Riccia  is however very simple and lacks a stalk. It remains embedded within the thallus until the latter disintegrates, and the spores are then dispersed by water currents as the pond level rises, or on the feet of birds walking around in the mud.  Seeds of Drosera capillaris are probably dispersed in a similar way.
The sporophyte of Riccia is embedded within the gametophyte
thallus.  It consists of a thin wall (the capsule) containing a mass
of diploid tissue, which here has been transformed through
meiotic division into a number of hard-walled spores. From
Essig 2015, after Brown.

So the water-edge habitat has continued to host a dynamic community of ephemeral plants of similar growth form and reproductive habits since the very first colonization of the land.

Essig, Frederick B., 2015. Plant Life - a Brief History. Oxford University Press.


Wednesday, January 31, 2018

Flowers, Compound Flowers, and Superflowers

In the simple inflorescences of Indigo
(Indigofera spp., Fabaceae) new flowers
are produced at the tip for an extended
period of time, opening first at base, and
lasting only for a day or two.  Many
inflorescences with more complex
branching patterns still open just a few
flowers at a time.
An inflorescence can be defined as an aggregation of flowers on a specialized shoot that lacks ordinary leaves.  The lack of full-sized, photosynthetic leaves is the key to defining an inflorescence, as opposed to a series of single flowers along a leafy branch.  Within an inflorescence, leaves may in fact be present, but they are either smaller than normal, specialized in shape, conspicuously colored, or all of the above.

One common type of inflorescence, is one in which flowers open up one or a few at a time, for an extended period.  Examples include lupines, snapdragons, gladioli, and foxgloves.  Such inflorescences are adapted to induce "repeat visitors" - insects, birds, or other animals that remember the location of the plants and drop by each day to collect nectar or pollen from freshly opened flowers. This is a behavior known as trap lining.

In such flowers, a common means of avoiding self-pollination, is for the stamens and pistil within each flower to mature on different days. For example, pistils may be active and receptive to pollen on the day the flower opens, with the anthers opening to shed pollen 24 hours later. The common Amaryllis follows this pattern.
A common means of avoiding self-fertilization within individual flowers is to have pollen shed on one day (left) and stigmas receptive on another day (right).  This effectively makes the flowers male on one day, and female on another day.  

Compound, or false flowers, such as those of the sunflower family or the spectacular poinsettias, are actually condensed inflorescences adapted to look like a single large flower to pollinators, but still opening their flowers a few at a time to attract trap-lining animals.

In the compound flower heads of the Sunflower
Family, such as this Ice Daisy, the tiny flowers
(visible as the yellow rod-like structures)
around the outside of the central disk open first,
to be followed by flowers progressively closer
to the center.
In other inflorescences, the flowers mature all at once to create a single, massive pollination event.  I like to call these "superflowers." Super flowers don't necessarily look like a single flower, but they behave like one.  In the most specialized of these kinds of inflorescences, flowers are unisexual, and the opening of the male and female flowers is offset, such that the entire inflorescence behaves as a single, short-lived flower. Examples of these are found most spectacularly in the Aroid and Palm Families.

The Titan Arum, Amorphophallus titanum,
blooming at the U.S. Botanical Garden in
Washington, D.C., posted on Wikipedia.

The Titan Arum, which makes the news whenever it blooms in a botanical garden, produces a gigantic inflorescence in which all the tiny flower buds are mature when the large bract, or spathe, opens to reveal them.  They follow a similar strategy as the amaryllis flowers above, with separate female and male phases.  In this case, all the female flowers are active first, followed by the male flowers in a day or two.  This avoids self-pollination, as insects arrive during the female phase, bearing pollen from another inflorescence.  They then leave during the male phase, freshly dusted with new pollen.

Unlike the simple inflorescences
mentioned at the beginning of this post,
palm inflorescences complete most of
their development within their large,
protective bracts.  No new branches or
flowers will form after the bracts open. In
many, such as this Rhopaloblaste, the
flowers will continue to expand for a
while, and may open over a prolonged
period of time in order to attract trap-
lining insects. 
The inflorescences of palms, despite being rather large, appear to be fairly simple assemblages of small flowers, yet some of them behave in much the same way as the Titan Arum.  I made my discovery of these palm "superflowers" as a graduate student, first in Costa Rica, and later in New Guinea.

After waiting for a few hours at the edge of a swamp in Costa Rica, I found that inflorescences of a species of Bactris opened abruptly at dusk, displaying unopened male flowers and active female flowers nestled within them. The inflorescence emitted a musky odor, which attracted a variety of small flies, bees, and beetles. The male flowers opened to release their pollen 24 hours later. I observed the same thing in another species of Bactris later.

A year later, I was in Papua New Guinea and observed a nearly identical process in a species of Hydriastele.  I was able to get more detailed pictures of male and female flowers, along with their insect visitors, which I share below.

Though it consists of a number of branches, the inflorescences
of Bactris guineensis behave the same as that of the Titan Arum. Female
flowers, hidden among the larger male flowers, are
receptive to pollen soon after the large, fibrous bract opens.

When the bract of a Hydriastele microspadix inflorescence splits
open, the flowers are all mature, and arranged in triads of
two large male flowers with a tiny female flower between them.  


When the flowers are first exposed, the stigmas of the tiny female flowers, seen at the left between pairs of male flowers, are exposed, sticky, and receptive to pollen..  The male flowers (right) only open 24 hours later to release their pollen.  During the female phase, tiny flies and weevils are already present, attracted by the scent of the unopened male flowers.
One further example from the palm family comes from the mangrove palm, Nypa fruiticans, which lives in brackish water around river deltas and estuaries throughout the old world tropics. I spent a day observing them.  Here the female flowers, which are rather bare and uninviting, are borne in a tight globose head at the top of the inflorescence. Male flowers are borne on dense orange-colored spikes below the female flowers.  Brief observations suggested that pollination is accomplished by small flies that land first on the female flower heads, and then crawl down to the spikes of unopened male flowers where they lay their eggs.  Larvae develop within the spikes, feeding on the unopened male flowers, and mature in a few days.  When the new adult flies emerge, the male flowers have opened and are shedding pollen.  The flies are then covered with the sticky pollen and fly off to start a new cycle on another Nypa inflorescence.

Female flowers of Nypa form a dense globose head (left), and appear to provide no nutrition for insects.  The dense male spikes (right), however, provide a place for fly larvae to develop as they feed on the tissues of the unopened male flowers.

Mosses of Central Florida 45. Schwetschkeopsis fabronia

Schwetschkeopsis fabronia (Sull.) Broth. (Myriniaceae) is a creeping moss found at the bases of hardwood trees and on rocks. Leaves are scale-like and more-or-less pressed to the stem. Slender, whip-like shoots may also present.
A dried specimen of Schwetschkiopsis fabronia from the USF Herbarium (M. Newberry, s.n., 18 February 1971, Hillsborough River State Park). The scale-like leaves fold against the stem, making the shoots look like juniper twigs.

Leaf cells are long-oval, slightly bumpy on the upper surface due to projections of the cell walls at the upper end.  The midrib is lacking, very faint, or briefly double.  Spore capsules are upright and more-or-less symmetrical,but have been rarely collected.
The tip of the shoot, showing the short, scale-like leaves.
Light spots at the end of each cell indicate the
 characteristic projections of the thick cell walls.

This species is similar in appearance to Clasmatodon parvulus, but the latter has a distinct midrib.  Papillaria nigrescens is also similar, but with larger leaves, a more distinct midrib, and more elongate leaf cells, each with several papillae.

It is found in Florida from the panhandle southward to Highlands County.  Elsewhere, it is found throughout the eastern U.S., west to Texas, and also in the West Indies and Asia. 

Thursday, January 25, 2018

Mosses of Central Florida 44. Herpetineuron toccoae

Wet plants of Herpetoneuron toccoae growing in Macao.
Photo by Li Zhang, posted on the Southern
Illinois University website.
Herpetineuron toccoae (Sullivant & Lesquereux) Cardot (Anomodontaceae) is a creeping moss found on tree bases and rocks.

The leaves spread on both sides of the stem when wet, like other common mosses, such as Isopteryigium, but roll inward and press to the stem when dry.  The leafy shoots also tend to curve to one side when dry.  The leaves also have a distinct midrib, which is somewhat wavy as it approaches the toothed tip. Leaf cells are ovate-angular. It is not known to produce spore capsules in the U.S.

The midrib of the leaf is a bit wavy toward the slightly toothed tip. From a
dried herbarium specimen, Griepenburg 130, USF.

This pantropical species occurs throughout the southeastern U.S., north to Illinois,  and has been reported from Arizona.

In Florida, it has been reported from Franklin Co and spottily in counties along the Gulf  Coast as far south as Hillsborough County.

Leaf cells are oval to angular.
Dried plants. Photo by Blanka Shaw, posted on Consortium of North
American Bryological Collections website.

Wednesday, January 24, 2018

What's killing our trees?

"Our industrial society with its attendant air pollution is slowly killing our forests, as it has the forests of eastern Europe, weakening and stressing trees, and making them more susceptible to cold winters and attack by pathogens."  Paul Donahue, in Tree Death and Forest Decline.
Dying forests in eastern Europe. Photo by Lovecz, posted on Wikimedia Commons. 

Forests in the eastern U.S., the Rocky Mountains, and California are all seeing massive death of forest trees.  This in turn adversely affects the survival of other plants, as well as of animals dependent on those trees, and biodiversity is seriously diminished.  Yet there are misconceptions, put out deliberately by special interests or arising from ignorance, about what exactly is killing our forests. 

Donahue continues:

"One criticism often leveled by opponents of stricter air pollution standards is that acid rain or other pollutants don't kill trees, that they are actually killed by cold winters or by insects or fungus or some such agent." 

Those who lobby for relaxing pollution standards are using carefully selected facts out of context to support a particular agenda (one of the tools of pseudoscience). It is true that the trees in forests like those above are killed by insects, pathogens and extreme weather, but what is carefully ignored is the fact that such death is greatly increased after the trees have been seriously stressed or weakened by air pollution or changing climate patterns.

In the eastern U.S., as discussed in detail by Donahue, the immediate cause of death has often been severe weather, but trees that have been weakened by acid rain are more prone to damage than healthy trees.  Acid rain results from burning sulfur-containing fossil fuels by industry and from the nitrogen oxide component of automobile exhaust.

In the Rocky Mountains, the Sierra Nevada, and elsewhere in the west, the Mountain Pine Beetle is often blamed.  But this a native species of insect that has been here for thousands of years.  Beetle larvae overwintering below the outer bark of the trees are normally killed by cold weather, keeping the populations under control. They are having a much greater impact now because of higher than normal temperatures and lower rainfall in the past ten years, which also stresses the trees. These changes are part of overall global climate change. 

There is a misconception about climate change, voiced frequently by ignorant government officials, that it will be expressed as a uniform and consistent warming everywhere.  Climate change actually results in a complex array of disruptions that include more temperature and precipitation extremes, both up and down.  So vicious winter storms and extreme low temperatures are part of that disruptive pattern.

The planet is indeed warming overall, as is evident in the melting of the polar ice caps, which in itself will result in complex repercussions in oceanic currents and climate patterns, as well as the rising sea levels that threaten coastal human populations and entire low-lying nations.

"Those who deny the existence of climate change and rising sea levels, who want to do away with environmental protection agencies, who oppose treaties on clean air and reduction of carbon emissions, and who want to open up national parks and other wild lands to mining and other economic exploitation, just don't get it, and must be rejected."

This quote is from my October 2016 essay on endangered species and population growth.  Unfortunately, the fears expressed have been chillingly born out. The current governmental leadership in the U.S. is moving rapidly backwards on issues of air quality, climate change, and protection of public lands.  

Americans have another opportunity in the upcoming congressional elections to choose more environmentally supportive representatives.  Can those of us who understand and respect science, and who care about the environment and biodiversity, make a difference?

Given the many highly publicized and polarizing issues grabbing voter attention this year, it may seem hopeless.  But even if we can tip the scales on some tight congressional elections, even helping elect one or two conscientious representatives, we can make a difference.  You can help in a number of ways:

ASK your representatives or candidates what their stand is on air quality standards and other environmental issues.

EDUCATE your current representatives about important environmental issues and urge them to do the right thing.

If they will not be educated, REPLACE them.  Support candidates who understand the issues and will stand up for them.

VOTE for the best available candidates, Democrat or Republican.  

Though environmental protection has in recent decades has been associated primarily with the Democratic Party, an exchange of letters in a recent Sierra Club Magazine demonstrated that many conservatives also cherish our natural heritage and support the Club's fundamental mission.  This was expressed some time ago in a post from the Missouri chapter of the Sierra Club (click here).  In fact, an organization called Republicans for Environmental Protection (now called ConservAmerica) was established in 1995.  

The primary elections in both parties are the first opportunity to bring better candidates forward.  Republican candidates who support the environment particularly need support.

If you are among the many readers of this blog who do not reside in the U.S., do what you can in your own elections when they come up, and best of luck.  All nations must work together to protect our global ecosystem.

Saturday, January 20, 2018

Mosses of Central Florida 43. Micromitrium

There are three species of Micromitrium (Ephemeraceae) in our area: M. megalosporum Austin
Micromitrium tenerum at a drying pond edge.  Permission pending from
Okayama University of Science,
M. tenerum (Bruch & Schimp.) Crosby and M. synoicum (James) Austin.  These are tiny short-lived plants that form sparse colonies on bare soil along drying pond edges.  The plants form rosettes with a single, globose sporangium nestled among the leaves.  Their leaves lack a midrib and the leaf cells are elongate, somewhat curved (worm-like) and smooth.

They are similar to Ephemerum crassinervium, which is in the same family, but that species has leaves with  distinct midribs, more ovoid capsules, and papillose cells near the tip of the leaf.

The ranges of the three species overlap, as they all occur throughout eastern North America. M. tenerum has been also reported from British Columbia, and M. synoicum from Oregon.  In Florida, they are all found primarily in the panhandle region, with reports from as far south as Polk County. None are collected very often, however, as they are short-lived and hard to see.

In M. megalospermum the leaves are broadly ovate and the spore capsule opens irregularly, while in M. synoicum and M. tenerum the leaves are lance-shaped, and the capsules open along a distinct ring around the middle or above.

In M. synoicum the leaves are erect, with smooth, somewhat incurved margins and have distinct stems below the crown of leaves, while in M. tenerum the leaves are spreading, with flat margins, and teeth at the tips, and the plants are stemless.

Thursday, January 11, 2018

Mosses of Central Florida 42. Papillaria nigrescens

Papillaria nigrescens (Hedwig) A. Jaeger (Meteoraceae) occurs on tree bark in shaded, humid hammocks.  It's leaves are scale-like and pressed against the stem, giving the yellowish to blackish leafy shoots the appearance of tiny juniper twigs.  Some shoots have drooping, whip-like extensions with sparser, smaller leaves, or are nearly naked with a small tuft of leaves at the ends.  This species is not known to produce spore capsules in our area.
Dried specimen of Papillaria nigrescens, collected in Hillsborough River State Park on bark of hardwood tree (Griepenburg 10, USF) 

The main leaves are ovate, but gradually narrowing to a sharp tip.  Leaf cells are narrowly-ovate and tapered, and somewhat wavy (worm-like) with papillae (hard, translucent bumps). The midrib reaches to about mid-leaf, though may not be very distinct.
The scale-like leaves of Papillaria gradually taper to a sharp
tip. A faint midrib extends a little more than half the leaf

This species has been found throughout Florida, but collected only occasionally.  It occurs throughout the New World tropics, and elsewhere in the U.S. it has only been found in southern Louisiana. It has previously been known as Meteorium nigrescens.
Leaf cells in Papillaria are elongate, tapered and somewhat wavy.  The papillae (hard, translucent dots) can be seen lined up along the length of each cell.