掌叶海金沙 zhang ye hai jin sha

Hydroglossum longifolium Willdenow, Abh. Kurfüstl.-Mainz. Akad. Nützl. Wiss. Erfurt 2(4): 22. 1802; Lygodium derivatum Alderwerelt; L. digitatum C. Presl; L. teysmannii Alderwerelt.

Rhizome shortly creeping, apex of rhizome and bases of stipes covered with shiny black hairs. Juvenile fronds once or twice dichotomous, pinnae palmately divided with 4-7 subequal lobes, base often ± cordate, lobes up to ca. 18 × 1.8 cm, acuminate, margins shallowly serrate, with a vein ending in each tooth. Scandent fronds up to ca. 4 m, rachis up to ca. 2 mm in diam.; primary rachis branches very short, with a dormant apex covered with brown hairs having small swollen multicellular bases; secondary rachis branches 1-3 times dichotomous or subpinnate (lowest ones sometimes simple and bearing large 6-lobed pinnae); sterile pinnae composed of 2-4 subequal lobes ca. 15 cm or longer and ca. 15 mm wide, sinuses between lobes reaching up to 15 mm from base of pinna, surfaces glabrous and usually not warty when dried, base cuneate to cordate, margins regularly serrate, not or slightly thickened; fertile secondary branches 1-3 times dichotomous or (if dichotomies unequal) ± distinctly pinnate with 2 dichotomous tertiary branches (tertiary branches rarely with 3 separate pinnae); fertile pinnae simple or more often usually consisting of 2 subequal lobes united at base, lamina 3-10 mm wide, sorophores commonly 2-3 mm, less often up to 6 mm; spores coarsely and irregularly verrucose with prominent laesura and equatorial ridge on proximal face.

Forest margins, probably in more exposed places than Lygodium circinnatum. Hainan, Taiwan [S India, Indonesia, Malaysia, Philippines].