Lab 2: Seed Free Vascular Plants

 

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The seed-free vascular plants are often referred to as the cyrptogams. Note that this is 'cryptogams,' not 'cryptograms...' the etymology is from the words for hidden (crypto, the same root for cryptic, crypt, etc.) and marriage (gam, as in gamete) - a phrase first used by Linnaeus. In other words, these plants' sexual parts are relatively inconspicuous - they are flower and seed free. Both generations, gametophyte and sporophyte, are independent at maturity. The sporophyte is what we typically think of when we think of “ferns” and is the generation you will be working with.

In general, ferns are sparsely represented in our teaching plant collection. If someone would like to specialize in collecting ferns please see your TA. Extra credit may be available for good specimens of certain species.

The best way to identify Wisconsin's cryptogams is online at the UW Green Bay site devoted to ferns and their allies. It has a nice key and species descriptions, but the placement of genera into families can be different from what we follow and what other websites use. Another good website is that from the University of Michigan Herbarium - based on the Field Manual of Michigan Flora.

There are a few references worth checking out if you are interested in pursuing ferns and fern allies (the vascular cryptogams) further:

Flora of North America, vol 2. (in lab) but also available online. This is the standard for the present taxonomy of ferns and allies.

Peterson's Field Guides: The Ferns . An excellent and up-to-date key to ferns and their allies. Nicely illustrated.

The Ferns and Fern Allies of Wisconsin, by R.M. Tryon, N.C. Fassett, D.W. Dunlop, and M.E. Diemer. 1940. This is an old book, but the keys are very good, all groups treated in both vegetative and sexual conditions.

How to Know the Ferns: a guide to the names, haunts, and habits of our common ferns, by Frances Theodora Parsons. 1961. Also old, but many have learned ferns with this book in tow.

 

  Plants to key out:

1. Pteridium aquilinum (Dennstaedtiaceae) 'Bracken fern.'
The species is often described as "sensu lato" (= broadly defined) as it is a cosmopolitan species (except Antarctica) showing a lot of variation with some taxonomists wanting to split the species into several species ("sensu stricto"). It contains trace amounts of carcinogens, though for years people have eaten the fiddleheads. A single individual may be quite large, consisting of many above ground stalks joined by a thick rhizome.

2. Onoclea sensibilis (Onocleaceae) 'Sensitive fern'
A very common species in wetlands of all kinds, shaded or sunny. People will paint the sporangia of this species for use in decorative floral arrangements.

3. Huperzia lucidulum (Lycopodiaceae) 'Shining clubmoss'
Old name: Lycopodium lucidulum
Sometimes, through taxonomic revisions, the genus and even family affiliation of given plants can change. This species once belonged to another genus (senus lato !) which was recently split up. You may come across this more broadly defined genus in other manuals or online sources - do you know what it is? These plants have been used to make wreaths in the Christmas season, but are so heavily collected that they have been depleted in some areas of the country (e.g., in the northeast U.S.) and have since fallen under legal protection in at least some states.

 

  Species to learn

4. Adiantum pedatum (Pteridaceae) 'Maidenhair fern'
There are various stories about its naming whatever the story, a beauty. Grows in rich woodlands, rarely out of shade.

5. Polypodium virginianum (Polypodiaceae) 'Rock-cap fern'
Grows on big rocks, amongst other places. The species is often described as "sensu lato" as it is a circumboreal species showing a lot of variation. The family Polypodiaceae used to be a catch-all for many ferns, at one time or another several of the ferns you will have looked at today were placed in this family.

 

  Genera to learn

6. Athyrium (Athyriaceae) 'Lady fern'
Resembling a more delicate wood fern, this fern is common throughout the state in all but the wettest forests. The fronds taper to a delicate tip and have shaggy scales along the stipe. The sori are elongate and shaped like bananas or crescent moons. The indusia are folded over the spores.

7. Selaginella (Selaginellaceae) 'Spikemoss'
Also quite primitive, many species tending towards drier habitats in North America than the morphologically similar Lycopods. Growing to the size of bushes in the humid tropics. Has been marketed as the "Jesus Christ plant," because it can go for years without water, only to be revived by a good dousing, or "baptism." This plant might be inconspicuous but it is not uncommon, it has been recorded from almost every county in WI. Look for it anywhere you see prickly pear cactus (Opuntia) growing.

8. Equisetum (Equisetaceae) 'Horsetail'
Also called "scouring rush" because of the silica content of the stems. Early pioneers used them to clean their pots and pans, and reed intrumentalists use them today to hone their reeds. Dried out individual stalk pieces may be mistaken as cigarette butts in the field. [Equis- from the Latin for 'horse.']

9. Drypoteris (Dryopteridaceae) 'Wood ferns' or 'Shield ferns'
These are some of the most common ferns you will find in the woods of Wisconsin. Members of this genus range from twice to even four times pinnate, and their sori have prominent coverings, or indusia. Several members of the genus are evergreen.

10. Osmunda (Osmundaceae) 'Cinnamon fern' or 'Interrputed fern'
Osmunda are common roadside ferns, often found in moist ditches or culverts. They are easily distinguished by their dimorphic fronds, which bear separate sterile, photosynthetic pinnae, and fertile, non-photosynthetic pinnae. The common names 'cinnamon fern' (O. cinnamomea) and 'interrputed fern (O. claytoniana) refer to the appearance of the fertile pinnae, which are held erect on a wand-like frond which turns brown in the former, and which occur between two, 'interrupted' groups of sterile pinnae along the stipe in the latter.