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2. Alsophila R. Brown, Prodr. 158. 1810.
桫椤属 suo luo shu
Gymnosphaera Blume.
Plants treelike; trunk erect, rarely branching, or creeping, shrublike, apices covered with scales. Fronds large; stipe stramineous, dark brown, or black, smooth, spiny, or warty; scales brown or dark brown, margin differentiated; lamina 1-3-pinnate; veins simple or forked. Sori orbicular, dorsal on veinlets; indusia various in form or absent, paraphyses present. x = 69.
About 230 species: pantropical, extending into the S temperate zone as far as the subantarctic Auckland Islands; plants of cold or wet montane forests, on slopes or in ravines, and low canopy, middle understory, or ground cover; 20 species in Asia; 12 species (one endemic) in China.
Most species have an indusium, but this structure may be lost as the frond matures; in some species, the indusium is absent. The Chinese species in Alsophila subg. Alsophila all have an indusium; the species of A. subg. Gymnosphaera (Blume) Q. Xia are all without an indusium.
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| 1 |
Stipes stramineous, pale green, or brown, spiny or warty; fertile and sterile pinnules almost same size; lateral veinlets forked, bearing sori at forks; indusia developed, sometimes very small, scalelike, covered by sorus when mature; 16 spores per sporangium (A. subg. Alsophila) |
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(2) |
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Stipes, rachises, and costae black or red-brown, not spiny (except A. austroyunnanensis), slightly warty; fertile pinnules or segments normally narrow and smaller than sterile ones; veins simple; sorus without indusium; 64 spores per sporangium (A. subg. Gymnosphaera) |
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(6) |
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| 2 (1) |
Abaxial side of midvein of pinnules and segments with pale acicular hairs. |
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1 A. costularis |
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Abaxial side of midvein of pinnules and segments glabrous |
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(3) |
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| 3 (2) |
Indusia enveloping sori |
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(4) |
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Indusia almost covered by sori at base |
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(5) |
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| 4 (3) |
Stipes spiny; indusia open toward midveins. |
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2 A. spinulosa |
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Stipes not spiny; indusia not open toward midveins. |
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3 A. loheri |
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| 5 (3) |
Indusia flat, margin toothed. |
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4 A. latebrosa |
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Indusia scalelike. |
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5 A. fenicis |
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| 6 (1) |
Fronds dimorphic, or pinnae dimorphic; fertile pinnules or segments narrow; stipes spiny at base. |
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12 A. austroyunnanensis |
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Fronds monomorphic; stipes not spiny at base |
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(7) |
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| 7 (6) |
Lateral abaxial sides of stipes and rachises with spreading brown scales |
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(8) |
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Lateral abaxial sides of stipes and rachises without spreading brown scales |
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(9) |
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| 8 (7) |
Both sides of frond with acicular hairs. |
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6 A. andersonii |
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Both sides of frond glabrous. |
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7 A. gigantea |
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| 9 (7) |
Pinnules shallowly pinnatifid but not reaching halfway to costae, or only crenate. |
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8 A. podophylla |
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Pinnules pinnatifid more than halfway to costae |
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(10) |
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| 10 (9) |
Small scales on abaxial side of pinnules flat, not bullate. |
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11 A. khasyana |
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Small scales on abaxial side of pinnules bullate |
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(11) |
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| 11 (10) |
Scales at stipe base concolorous, golden-yellow; bullate scales on abaxial sides of costae and midveins of pinnules and segments, with a prominent dark tip. |
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9 A. denticulata |
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Scales at stipe base bicolorous, dark brown, with rather wide paler margins; bullate scales on abaxial side of costae, toward apex with acicular hairs. |
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10 A. metteniana |
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List of lower taxa
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