Selaginella rupestris

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Classification Hierarchy
Kingdom Plantae
Subkingdom Viridiplantae
Superdivision Embryophyta
Division Tracheophyta
Class Lycopodiopsida
Subclass Lycopodiidae
Order Selaginellales
Family Selaginellaceae
Genus Selaginella
Species Selaginella rupesris

BONAP, FNA, ITIS, USDA, VPI, NPGH

Scientific Name: Selaginella rupestris
. . . . . . . . . .Syn: Lycopodium rupestre
Common Name: Rock spikemoss
Origin: NATIVE
Notes: Selaginella is interesting evolutionarily. It looks like a bryophyte, which as a category; includes mosses, liverworts, and hornworts. Like the bryophytes it is not a flowering plant; rather, it produces spores. Unlike the bryophytes which lack vascular tissue: Selaginella shows a rudimentary vascular system called a protostele and it is heterosporus, that is, it produces two kind of spores (megaspores and microspores). The bryophytes and Selaginella are thought to be among the earliest of land colonizing plants. Please look over the FNA link above and the additional references below (There may be some pay walls).
Additional references: * 1, * 2, * 3, * 4, * 5, * 6, * 7, * 8, * 9, * 10.

Rock spikemoss-1

Field Marks for Identification:

Flowers: Spikemoss do not produce flowers, they produce spores, and represent an earlier history in plant evolution.
Leaves: Small leaves of two types; vegetative leaves and spore bearing leaves called sporophylls. Microsporophylls each support a microsporangium which contains microspores. Magasporophylls each support a megasporangium which contains the megaspores. The sporophylls produce a four sided upright structure called a strobilus (plural strobili). Both leaf types are about 2mm long and the leaves on a strobilus are nearly twice as wide as the vegetative leaves.
Glossaries of botanical terms: 1, * 2, * 3, * 4, * 5, * 6.


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Comments: You may have wondered where the microsporangia and the microspores are in the photos above. Since we are dealing with a single individual colony in a single species here, it is worth broadening the conversation a little further. S. rupestris is one of only two species that have been found in Iowa (the other is S. eclipes). The genus Selaginella probably includes more than 700 species, most of which are found in climates that are wetter and warmer than that of Iowa. Among the differences that distinguish these species is the way that the strobili are oriented. For example, in some species, such as S. rupestris, the strobili stand upright. In some they are angled upward, others are horizontal and some even dangle downward. In most of these cases the megaspores develop at a lower position on the strobili than the microspores. S. rupestris develops its megaspores on the lower part of the strobili and microspores may or may not be visible. When they are visible they are found above the megasporangia at the distal end of the strobili. ...To be continued.

In the meantime please visit this site and view the pdf. Here are a few photos to show the nature of the flood plain and the sandy soil.

floodplain1 floodplain2 floodplain3