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   Why ferns are hard to identify
   Nomenclature
Glossaries
   Illustrated Glossary
   Flora of Australia
   Lower Vascular Plant Glossary
Hardy Fern Glossary
   Rhizomes
   Structure and Shape
   Blade Division
   Hairs and Scales
   Margins
   Sori and Indusia
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    Adiantum  Arachniodes
    Aspidotis  Asplenium
    Astrolepis  Athyrium
    Blechnum  Cheilanthes
    Cryptogramma  Cyrtomium
    Cystopteris  Dennstaedtia
    Deparia  Diplazium
    Dryopteris  Gymnocarpium
    Lygodium  Matteuccia
    Onoclea  Oreopteris
    Osmunda  Pellaea
    Phegopteris  Pleopeltis
    Polypodium  Polystichum
    Pteridium  Pteris
    Pyrrosia  Thelypteris
    Woodsia  Woodwardia

Glossary: Rhizomes

Terminology for rhizomes is muddy. Among the many ill-defined terms are clumping, shuttlecock, ascending, erect, creeping, stoloniferous, running, rosette, and tufted. It is not hard to find several of these terms used for the same plant by either one author or different authors.

Here we use only three basic terms, with or without a branching qualifier.

erect: The plant has a clear center, fronds surrounding that point. Polystichum andersonii is strictly erect, in this case approaching a tree fern in form.Polystichum andersonii
 On the site Woodslore, created by Bors Vesterby, you can find a magnificent portrait with a little hunting.
erect, branching: While young the plant will be of the form above. Later, branching of the rhizome can lead to two effects. Short branches give a less-centered, more amorphous crown, and the difference between this and the following may not be observable above ground. However, if the branches are longer, the effect is dramatic, as with Matteuccia struthiopteris, a classic erect and branching rhizome. Matteuccia struthiopteris
 Photo by Anna Lena Anderborg in full size at Den virtuella floran.
short-creeping: Fronds are generally less than about 1 cm distant, branching is usual, and often unstated. Blechnum penna-marina branches almost as often as it throws up a new frond.Blechnum penna-marina
 This photo is by John and Hillary Birks and is seen to better effect on their web site.
long-creeping: Fronds are generally more than 1 cm distant, branching is usual, and often unstated. Pteridium aquilinum forms extensive colonies, and is the most cosmopolitan, some would say weediest, of ferns.Pteridium aquilinum long-creeping rhizome
 This drawing by Kirsten Tind is given full display on the Pteridium aquilinum page.

Rhizome Indument

The bulk of the rhizome is often below ground, so inspection of its surface hampered. However, the apex of the rhizome is more commonly above ground, even if visibility is impaired by old stipe bases. In some ferns, the nature of the indument can be highly diagnostic, so worth a little effort. Here are the types encountered.

clathrate scales
In these scales the individual cells have thick margins, giving a stained glass effect to the scale. This is diagnostic for Asplenium; there are occasional ferns outside Asplenium with clathrate scales, but none on this site.
peltate scales
These scales are attached below their centers. This is diagnostic for Polypodium.
scale-leaves
Matteucia has scale-leaves on its runners.
other scales
Most of the remaining genera have scales on the rhizome, and they are often similar to the scales on the stipes, handy if you cannot see them.
hairs
The genera Dennsteadtia, Pteridium, Lygodium, and Osmunda have hairy roots or rhizomes.
absent
Gymnocarpium has glabrous rhizomes.
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