A Grammatical Dictionary of Botanical Latin

Cerastes,-ae (s.m.I)): > Gk. kerastEs, ‘horned’; “a horned serpent, the cerastes: Coluber cerastes L.; “as an attribute of the hair of the Furies; a kind of horned worm injurious to trees” (Lewis & Short); the horned serpent, [viper], or asp, Cerastes cornutus (Glare) [Gk. kerastEs,-ou (s.m.II): ‘horned,’ e.g. of a ram; of the god Pan; there is a feminine kerastis-idos (s.f.III), abl.sg. kerastide: as noun: the horned serpent or asp, Cerastes cornutus: also, a pest which destroys fig-trees” (Liddell & Scott).

Some species of the snake, genus Cerastes, have a spine-like scale (the ‘horn’) above each eye. The gender of the genus name appears to be masculine (Cerastes cornutus; also Pseudocerastes persicus). The epithet of Cerastes vipera appears to be a noun in apposition (vipera,-ae (s.f.I).

Cerastes,-ae (s.m.I), horned serpent:

       singular  plural
Nom.  cerastes   cerastae 
Gen.  cerastae    cerastarum
Dat.  cerastae   cerastis
Acc.  cerasten   cerastas
Abl.  ceraste    cerastae

NOTE: a Latin first declension masculine noun somewhat irregular in the singular; the endings in the plural are standard first declension plural endings; see first declension.

Ceanothus sect. Cerastes

FABACEAE: Acacia cerastes [noun in apposition; syn. Racosperma cerastes]; a shrub with tortuous branchlets, rudimentary phyllodes appear as small horn-like projections.

ORCHIDACEAE: Masdevallia cerastes [the Horned Snake Masdevallia, alluding to the flower-shape] = Megema cerastes; Ophrys cerastes, an orchid with extremely long horns, i.e. lateral sepals linear, horn-like; cf. Orthoceras,-atis (s.n.III); > Gk. orthos, straight + ceras,-atis, horn, alluding to the upright lateral sepals.