Lycopodiaceae

Øllgaard, Benjamin & Testo, Weston, 2021, The Lycopodiaceae of Panamá, Phytotaxa 526 (1), pp. 1-66 : 4-5

Key­­­to­­­the­­­genera­­­of­­­ Lycopodiaceae ­­­in­­­ Panamá

1. Stem dichotomies equal (isotomous) throughout, without elongate, indeterminate main stems; roots usually forming one basal tuft; sporophylls and vegetative leaves alike, or the sporophylls, if smaller, persisting and green, not subpeltate and ephemeral; sporangia axillary; spores foveolate-fossulate. ............................................................................................................ Phlegmariurus

1. Stem dichotomies unequal (anisotomous) throughout (shoots pseudomonopodial), the branches differentiated into elongate, indeterminate, rhizomatous, or creeping, looping, trailing or scandent main stems, rooting at intervals, and usually determinate branchlet systems; sporophylls strongly modified, ephemeral, unlike vegetative leaves, subpeltate or peltate, aggregated in compact, terminal strobili; sporangia borne on sporophyll bases or axillary, spores reticulate or rugate..........................................2

2 Strobili sessile, pendent or nodding, terminating amply branched aerial branchlet systems....................................... Palhinhaea

2. Strobili sessile or pedunculate, erect, terminating simple, erect branches or ascending branchlet systems.................................3

3. Branching of horizontal shoots flabellate; creeping shoots anisophyllous with wide and long lateral leaves and narrow dorsal leaves; strobili terminating simple branches that arise dorsally on the creeping stems; sidewalls of sporangial epidermal cells straight, non-lignified, except for semiannular internal thickenings .............................. Pseudolycopodiella

3 Branching dorsolateral throughout, strobili sessile or pedunculate, terminating main branchlets ........................................4

4. Shoots terete, isophyllous, leaves borne usually in 12–20 indistinct longitudinal ranks with a hyaline apex; sidewalls of sporangial epidermal cells lignified, strongly sinuate, with alternating in-and e-vaginations, spores reticulate on all faces. ..................................................................................................................................................... Lycopodium s. str.

4. Shoots dorsiventral, anisophyllous, leaves borne in 4–5 usually distinct ranks ..............................................................5

5. Branchlet leaves opposite, borne in 4 ranks, one dorsal, two opposite lateral ranks and one ventral rank................. ............................................................................................................................................................. Diphasiastrum

5. Branchlet leaves alternating, borne in two dorsal alternating ranks of wide leaves, and 2–3 ranks of ventral, narrow, membranous-tipped leaves. ....................................................................................................................... Diphasium