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

366 PTERIDACEAE
blades, marginal or submarginal; margins of ultimate segments (= smallest subdivisions) of
leaf blades recurved to form false indusia (except in Astrolepis).
AThe taxa included here in the Pteridaceae have been variously treated at the family level. For
instance, some authorities (e.g., Carlquist & Schneider 2000a) segregate Cheilanthes and close
relatives into the Cheilanthaceae, while others (e.g., Lellinger 1985) recognize some of the genera
as Sinopteridaceae. We follow Windham’s (1993a) treatment (slightly modified to include
Ceratopteris—see discussion under that genus) and recognize the Pteridaceae as a cosmopolitan
family of ca. 40 genera and ca. 1,000 species. Six genera occur in East TX. The newer name
Adiantaceae has sometimes been applied to the family.
FAMILY RECOGNITION IN THE FIELD: plants typically growing on rocks (except 1 species aquatic or
semi-aquatic); sporangia at or near margins of the ultimate leaf segments with the leaf margins
usually recurved over sporangia to form false indusia (except in Astrolepis).
REFERENCES: Correll 1956, 1966a; Tryon et al. 1990; Windham 1993a; Gastony & Rollo 1998;
Carlquist & Schneider 2000a.
1. Plants aquatic or semiaquatic; leaves distinctly dimorphic (the fertile quite different than the
sterile); leaf blades with adventitious buds or small plantlets in notches along margins _________ Ceratopteris
1. Plants mostly on rocks, sometimes terrestrial; leaves usually monomorphic or in Pellaea somewhat
dimorphic; leaf blades without adventitious buds or plantlets.
2. Margins of ultimate leaf segments (= smallest subdivisions of leaf ) not recurved to form false
indusia; leaf blades 1-pinnate to 1-pinnate-pinnatifid throughout; lower (= abaxial) leaf surfaces
densely covered with coarsely ciliate or stellate scales; upper (= adaxial) leaf surfaces
usually with coarsely ciliate or stellate scales __________________________________________ Astrolepis
2. Margins of ultimate leaf segments recurved to form false indusia; leaf blades 2–5 pinnate at
least at base OR at least partially 2-pinnatifid (1-pinnate in 1 species of Pteris); lower leaf surfaces
scaly, pubescent, or glabrous; upper leaf surfaces without coarsely ciliate or stellate scales.
3. Rachis conspicuously winged in at least the distal 1/2 of leaf blade; leaf blades divided at
most so that they are 2-pinnatifid (usually at least some pinnae are deeply palmately
3-divided) ______________________________________________________________________ Pteris
3. Rachis not winged; leaf blades more divided, 2–5-pinnate at least at base.
4. Ultimate leaf segments with only the apical margin recurved; sporangia borne directly
on underside of recurved apical margins of ultimate leaf segments (= borne on the
false indusium); veins of ultimate leaf segments prominent, dichotomously branched
(= equally 2-forked), essentially parallel near the margins ____________________________ Adiantum
4. Ultimate leaf segments with apical and lateral margins recurved over sporangia; sporangia
borne on lower leaf surface and covered by the recurved margins (= borne on
blade tissue beneath the false indusium); veins of ultimate leaf segments obscure or, if
prominent, pinnately branched and more divergent near the margins.
5. Leaf blades usually 1-pinnate distally (2-pinnate below), glabrous on lower surface or
nearly so; largest ultimate leaf segments � 4 mm wide _____________________________ Pellaea
5. Leaf blades 2–more pinnate or pinnate-pinnatifid nearly throughout, usually tomentose
on lower surface (except sparsely pubescent to nearly glabrous in Cheilanthes
alabamensis, C. aemula, and Argyrochosma microphylla) OR lower surface covered with
conspicuous whitish powdery material; ultimate leaf segments � 4 mm wide.
6. Leaf blades with conspicuous whitish powdery material and without pubescence
abaxially __________________________________________________________ Argyrochosma
6. Leaf blades lacking conspicuous whitish powdery material, often (but not always)
tomentose abaxially.
7. Leaf blades glabrous abaxially; most distal ultimate segments of leaf blades �
cordate at base and attached only by distinct dark-colored stalks __________ Argyrochosma