A Grammatical Dictionary of Botanical Latin

sigmoideus,-a,-um (adj.A): sigmoid, i.e. curved like the letter S, 'ess', s-shaped; “having a form somewhat resembling the letter S” (Lindley) [> Gk. sigma (s.n.II), indeclineable, the Gk. Letter ‘s’]; see zigzag.

NOTE: in some combinations, authors have invented 'sigmat-, sigmato-,' assuming the stem is declineable from a stem sigmat-; but as the noun 'sigma' is indeclineable, the stem is 'sigm-' or 'sigmo-.' - valvae plus minus sigmoideae, valves more or less sigmoid (Stearn).

- striis foliaribus sigmoideis, with the leaf striae sigmoid.

- valvae capsulares subsigmoideae, the capsular valves somewhat sigmoid.

Sigmoideomyces; Sigmatomyces.

Acianthera sigmoidea; Aloe sigmoidea; Astragalus sigmoideus; Coleus sigmoideus; Bulbophyllum sigmoideum, Calonema sigmoideum.

Bactris concinna var. sigmoides; Corydalis sigmoides.

Vigna sect. Sigmoidotropis (Fabaceae) > Gk. sigmoid-, s-shaped + -tropis,-idis (s.f.III), keel.