An image of Fissidens taxifolius illustrating the basic flattened shoot structure of the genus, with doubled leaf. Image by Ralf Wagner. |
As in most large moss genera, the individual species are distinguished by technical characters, mostly microscopic features of the foliage, and can only be definitively identified by experts. However, there are some shortcuts that can help narrow down the choices in the relatively small number of species found in Florida (there are 450 species world-wide, 37 in North America), including the habit and length of the capsule stalks.
A dried specimen of Fissidens pallidinervis in the herbarium at USF. Note the relatively short stalks of the capsules (sporangia), and the twisted dry leaves. |
From the other 19 species it is distinguished by a combination of details, mostly of the leaves. The cells of the leaf, on either side of the prominent midrib, are tiny, roundish and papillate, which means they bear small, translucent bumps on their surface. This species has 2 or more such bumps, while some species have only one, and others have none (are completely smooth).
A single shoot from the specimen above. Note that three sporangia are rising from a single point on the stem. |
The leaf cells of Fissidens are small and roundish. In this view, the papillae can be detected as tiny bright spots of lighter green. |
Provisional short-cut key to the species of Fissidens in Florida.
1_Aquatic
2_Sporangium stalks .5-.6mm………….F. fontanus
2_Sporangium stalks .7-1.5 mm……….F. hallianus
1_Terrestrial
3_Sporangium stalks less than 6 mm long
4_Occurring on bark, tree bases, not soil-specific
5_Sporangium stalks to 2 mm long
6_Leaf cells rounded or with one papilla; bases of trees, cypress swamps
…………………..............……..F. leptophyllus
6_Leaf cells with several small papillae; bases of trees.....…F. pallidinervis
5_Sporangium stalks 3.5-5 mm long
7_Leaf cells smooth to 1 papillate
8_Leaves up to 6 pairs, markedly toothed, cells 1-papillate; on bark, logs, cypress trees…....F. serratus
8_Leaves up to 25 pairs, not toothed, cells smooth to rounded; Bark, tree bases, rotten wood .................….F. santa-clarenis
8_Leaves up to 10 pairs, minutely toothed, leaf cells smooth to bulging; bases of trees, soil............................…....... F. amoenus
7_Leaf cells with several small papillae; leaf apex ending in a sharp, clear cell, on soil, banks, roadsides, uprooted trees …….F. elegans
4_Occurring on calcareous soil or rocks
9_ Found throughout Florida
10_ occurring primarily at bases of trees; leaves in a pinnate pattern, up to 28 pairs
..........................................F. subbasilaris
10_ on moist limestone in ravines; Leaves in a palmate pattern, up to 12 pairs .
......................................................F. zollingeri
9_Found in north Florida only; on wet soil or rocks along streams,
11_ Found in Florida panhandle *;soil, rocks and stones in shaded ravines ………......................................................……..………..F. pellucidus
11_Found in northern peninsular Florida, stems branched,........F. obtusifolius
11_Found in northern peninsular Florida*, stems unbranched …F. minutulus
3_Sporangium stalks to 10-11 mm long
12_Capsules somewhat asymmetric, 1 mm long; occurring on bare, often clay, soil
.......................................................................................….. F. bushii
12_Capsule 1.8 mm long; occurring at bases of trees, roots…......... F. dubius
12_ Capsules symmetric; bases of trees, soil, logs .................…….F. bryoides
3_Sporangium stalks to 15 mm long
13_ Capsules to 2.5 mm long, symmetric; on calcareous soil, north Florida only
................................………………..F. polypodioides
13_ Capsules to 1.5 mm long, asymmetric; seeps, moist rocks, soil; central Florida
3_Sporangium stalks to 25 mm; on seeps and rocks with dripping water……….. F. adianthoides
3_Sporangium stalks to 17 mm; on moist soil .humus, .rocks ................................…….. F. taxifolius
*Questionable records of F. pellucidus and F. minutulus in Collier County, far removed from their north Florida ranges