臺灣野生植物資料庫

Terrestrial, epiphytic or epilithic annual or perennial, rarely climbing. Stems and roots dichotomous, growing points not protected by scales. Roots (including rhizophores and active root parts) arising from the axils of branches. Stems creeping, prostrate or caulescent, rarely a single, erect stalk; with or without dorsoventrality. Leaves spiral, sterile ones (trophophylls) in most species dimorphic and arranged in four ranks; fertile ones (sporophylls) monomorphic or, much rarely, dimorphic; usually condensed in strobili. Strobili terminal on ultimate branches; usually (1) quadrangular and sporophylls arranged in four ranks, rarely cylindric and sporophylls arranged spirally, or (2) complanate and sporophylls arranged in four ranks but dimorphic. Sporangia dimorphic, megasporangia usually tetrahedral with four megaspores; microsporangia reniform or shell-form, with numerous microspores. (Homing Chang 2012)