The Lycopodiales of the British Isles (Isoetes, Lycopodium, Selaginella)


L. Watson and M. J. Dallwitz

Diphasiastrum complanatum (L.) Holub.

Lycopodium x issleri (Rouy) Domin, L. complanatum auct Brit., L. alpinum var. decipiens Syme. Supposedly = L. alpinum x L. complanatum L.

Morphology. Stems elongated, with numerous small leaves; creeping, and rooting directly at intervals along their length; ostensibly monopodial vegetatively; with strongly flattened branches; without secondary thickening. Leaves eligulate; strongly 4-ranked on the branches (in alternating, opposite pairs, only slightly glaucous); 2–4 mm long; not hair-pointed.

Homosporous. Sporophylls differing markedly from the foliage leaves; aggregated into well defined terminal cones. Cones solitary, sessile at the tips of the normal shoots. The sporangia basal and subsessile on the adaxial surfaces of the sporophylls, non-septate.

Ecology and distribution. Lowland, upland and montane; heaths and moors. Curiously, the supposed parental species L. complanatum is no longer listed as British, it now being assumed that early records represent the hybrid.

Comments. More robust in habit than D. alpinum, and more glaucous.

Classification. Family Lycopodiaceae.

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2007 onwards. The Lycopodiales of the British Isles (Isoetes, Lycopodium, Selaginella). Version: 1st September 2009.’.