Thursday, July 20, 2017

Mosses of Central Florida 24. Anomodon minor

Anomodon minor has creeping  primary stems with short, scale-like leaves
and semi-erect branches with larger, tongue-shaped leaves. Photo from dried
herbarium specimen: Merner s.n. 15 June 1979 (USF)
Anomodon minor (Hedwig) Lindberg (Anomodontaceae) is a creeping moss occurring on bark at the bases of trees.  It is distributed widely in North America, extending south to Hillsborough and Polk Counties in central Florida. It has
Capsules of Anomodon minor are erect (unbent) and symmetrical.
Photo courtesy Robert A. Klips, Ohio Moss and Lichen Association.
two orders of leafy stems.  The primary stems creep horizontally along the substrate, and bear relatively short, scale-like leaves, while branch stems are semi-erect to spreading, with larger, tongue-shaped leaves. Branch leaves are broadly rounded at the tip with a short, hard point, have a distinct midrib, and the cells are small, roundish, and papillate (with hard, translucent bumps). When dry, the leaves fold against the stem. Capsules are erect and essentially symmetrical.  In habit and leaves, it somewhat resembles members of the Thuidiaceae, into which this genus is sometimes placed, but in that family, primary stem leaves are larger than the scale-like branch leaves, in both types of stems there are leaf-like paraphyllia between the true leaves, and capsules are asymmetric and bent to the side.

Within the Anomodontaceae, Anomodon is distinguished from the only other genus, Herpetineuron, by the shape and other features of the leaves. In Herpetineuron, leaves gradually taper to a point and the cells are smooth, without papillae.  Three other species of Anomodon occur in Florida.  A. tristis appears to form thinner mats, occurs higher up on tree trunks, and is found only in the northern part of the state. A. attenuatus forms denser mats, with more frequently branched stems that lay more-or-less flat, and taper at the ends with increasingly smaller leaves.  In A. rostratus, leaves are long and taper to a fine, hair-like point.
Leaves of Anomodon minor are elongate, tongue-shaped and with a rounded
tip with small hard point. Cells are tiny, roundish and equipped with papillae.
Lighter streak in the center is the midrib. 

Thursday, July 6, 2017

Mosses of Central Florida 23. Hygroamblystegium varium

Hygroamblystegium varium (Hedw.) Mönk.(Amblystegiaceae) is another moss frequently found in aquatic habitats in central Florida, along with Leptodictyum, Fontinalis, and species of Fissidens. Its leaves are shorter and spread more 3-dimensionally around the stem than those in Lepidodictyum, and the stems branch more frequently. Fontinalis is easily distinguished from these genera as its leaves lack a midrib altogether. The leaf cells in Fontinalis are also more elongate and curved, and the stalks of the sporangia (capsules) are extremely short.  Fissidens, of course, is easily recognized by the smaller secondary leaves attached at each node with the main leaves.  Like Amblystegium and Leptodictyum, which are in the same family, the capsules of Hygroamblystegium are erect, but slightly curved, and arise from short stems along the creeping main stems.
Compared to the related genus, Leptodictyum, the stems branch more frequently in Hygroamblystegium, and the leaves
are shorter, more scale-like, and distributed 3-dimensionally around the stem.  The capsule is upright, but slightly curved and asymmetric.  From a dried specimen, Wagner-Merner s.n., 17 May 1969 (USF).

Leaf cells of Hygroamblystegium are short-rectangular or sometimes
more elongate.
The family Amblystegiaceae is one of many moss families in taxonomic flux.  Even the treatment in Flora North America (FNA) is self-proclaimed to be tentative, with the treatment of genera and species still controversial and unsettled. Hygroamblystegium and Amblystegium, each containing only one recognixed species, are weakly separated, and sometimes combined into a single genus. The principal differences noted in FNA are that the leaves of Amblystegium are smaller than those of Hygroamblystegium and the midrib is weaker, and that the plants lack paraphyllia (extra leaf-like or thread-like appendages between leaves).  Amblystegium is also said to be always terrestrial, while Hygroamblystegium is often (but not always!) aquatic.  By this definition it appears that Amblystegium serpens is found only in north Florida, and reports from central Florida need to be investigated.

A lucky shot of the tip of the capsule of Hygroamblystegium varium.
In herbaria, Hygroamblystegium varium is more likely to be filed under Amblystegium, and it might be best to leave them there until the taxonomic dust settles. Some other species have been recognized, including Hygroamblystegium tenax, H. fluviatale, H. humile, H. trichopodium, and H. noterophilum, but it seems clear that these are all just variants of  the aptly named H. varium.