keys to the vascular plants of east texas - Botanical Research ...

312 KEY TO FERNS AND SIMILAR PLANTS
18. Plants stout, to 1 m or more tall; leaf blades triangular in
shape or nearly so, with 3 main divisions (each division
usually bipinnate); petioles greenish or ± straw-colored;
stems and petiole bases with slender hairs but without
scales ______________________ (Pteridium) Dennstaedtiaceae
18. Plants slender, usually 0.1–0.5 m tall; leaf blades neither
triangular nor with 3 main divisions; petioles often dark
brown or black; stems and petiole bases generally with
scales ________________________________________ Pteridaceae
17. Leaf margins never recurved to form a false indusium; sori
variously located on the abaxial (= beneath) leaf surfaces,
often near veins, occasionally near the margins of the leaves;
adaxial leaf surfaces without stellate or coarsely ciliate
scales.
19. Sori elongate along the veins; leaf blades 1-pinnate _____ (Asplenium)
Aspleniaceae
19. Sori round or variously shaped, not elongate (in our species,
except elongate in Athyrium with leaf blades 2pinnate-pinnatifid);
leaf blades in our species 1-pinnatifid,
1-pinnate, or more than 1-pinnate.
20. Leaf blades in our species only 1-pinnate or 1-pinnatifid,
the pinnae not further subdivided into
pinnules.
21. Leaf blades only pinnatifid (in our species), divided
nearly but not all the way to the rachis
(= midrib); pinnae essentially as wide at base
as towards their tips; margins of pinnae (in our
species) without any teeth or basal auricle; indusia
lacking _________________ (Pleopeltis) Polypodiaceae
21. Leaf blades pinnate, divided all the way to the
rachis; pinnae narrowed basally to a very narrow
petiole-like attachment to the rachis; pinnae
with small teeth on the margins, sometimes
with basal auricles; indusia present (but sometimes
shriveled at maturity) ____________ Dryopteridaceae
20. Leaf blades more than 1-pinnate, the pinnae themselves
either pinnate or pinnatifid.
22. Lower leaf surfaces with at least some transparent
needle-like hairs (particularly on the
costae and veins, sometimes even on the intervening
tissue or on the indusia—use hand
lens or scope); ultimate leaf segments often
(but not always) entire; petioles with 2 crescent-shaped
vascular bundles basally, distally
these united into a U-shape ___________ Thelypteridaceae
22. Lower leaf surfaces without transparent
needle-like hairs; ultimate leaf segments variously
incised, serrate, dentate, crenate, or lobulate,
not entire; petioles with 2 or more round
or oblong vascular bundles ____________ Dryopteridaceae