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

310 KEY TO FERNS AND SIMILAR PLANTS
3. Stems various, not naked, usually not green (except in Equisetum), erect OR not so, often un-
derground, not repeatedly branched dichotomously; leaves present, these varying from scalelike
to large and compound; sporangia not fused into a cluster.
4. Stems conspicuously jointed, green and hollow, the segments separating easily at the joints
(= nodes); leaves reduced to small essentially non-photosynthetic (non-green) scales in
whorls at the nodes; sporangia (= spore cases) in terminal strobili (= cone-like structures)
on stems without green leaves ______________________________________ (Equisetum) Equisetaceae
4. Stems not jointed, not green and hollow; leaves usually green; sporangia either on the
surface of leaves or leaf-like structures OR in terminal strobili on leafy stems OR in shortstalked
sporocarps at leaf bases.
5. Leaves simple, linear, grass-like or thread-like, the blades not expanded; spore-bearing
structures embedded in leaf bases or on very short stalks (1–2 mm long) at leaf bases;
plants often rooted in mud or in temporary pools.
6. Leaves tightly clustered together, arising from a corm-like rootstock, quill-like (larger
at base); sporangia embedded in the leaf bases, borne one per leaf _________ (Isoetes) Isoetaceae
6. Leaves scattered along a creeping rhizome, separate, not clustered, not quill-like; sporangia
in stalked (stalks 1–2 mm long), globose, hairy sporocarps (= nut-like or hard
bean- or pea-like sporangia-bearing cases) arising at the base of the leaves, the sporangia
numerous per sporocarp __________________________________ (Pilularia) Marsileaceae
5. Leaves compound or simple, with expanded blades OR leaves needle-like or scale-like,
neither grass-like nor thread-like; spore-bearing structures neither embedded in leaf
bases nor on very short stalks at leaf bases; plants rooted in various substrates including
mud or soil or on rocks or tree trunks.
7. Plants distinctly vine-like (CLIMBING FERNS); leaves with indeterminate growth, climbing,
vine-like, to 3(+) m long, the rachis elongate, twining, flexuous, stem-like (true
stem below ground); sporangia borne on finger-like lobes of the fertile pinnules (=
subdivisions of pinnae); species known in East TX from the s part of the Pineywoods
___________________________________________________________ (Lygodium) Lygodiaceae
7. Plants not vine-like: leaves various but neither climbing, vine-like, nor with a twining
rachis; sporangia variously borne, but not on finger-like lobes of the fertile pinnules;
including species widespread in East TX.
8. Leaf blades deeply 4-parted (resembling a 4-leaf clover), on petioles usually much
longer than the blades; sporangia in sporocarps borne near the base of the plant
__________________________________________________________ (Marsilea) Marsileaceae
8. Leaf blades variously compound or simple but not 4-parted; petioles usually much
shorter than leaf blades to absent; sporangia not in sporocarps near the base of
the plant.
9. Leaves 8 mm or less long; plants with numerous, small, usually overlapping or
divergent, scale-like or needle-like leaves, each with a single unbranched vein
(this type of leaf is a microphyll); stems well-exposed above the ground surface,
covered with the numerous small leaves; sporangia in the axils of the microphylls,
these microphylls often aggregated into cone-like strobili.
10. Sporangia in cylindrical strobili at the tips of elongate, distinctly erect, leafy,
fertile stems; leaves 4–8 mm long; plants homosporous (= with 1 spore type
of a single size) ______________________________________________ Lycopodiaceae
10. Sporangia in ± 4-angled strobili at the tips of leafy stems; fertile stems
ascending or spreading, not distinctly erect; leaves 1–3 mm long; plants
heterosporous (= with 2 spore types which are of different sizes) __________ (Selaginella)
Selaginellaceae
9. Leaves usually much more than 10 mm long; plants with relatively few large leaves
with numerous branched veins (this type of leaf is a megaphyll); stems underground
rhizomes or short crowns or caudices, not well-exposed above the ground