A Grammatical Dictionary of Botanical Latin

Thrum, also Thrumb, thrum-flower: “1. the filament of a stamen; 2. in Composite florets, the anthers” (Jackson): flos brevistylus, abl. sg. flore brevistylo. A thrum, usually applied to matters of weaving, is generally a short soft thread or tuft of threads. It may be applied to a hair, fiber or threadlike leaf or structure on a plant that resembles a thrum. “A heterostylic flower with a fairly short style and long stamens” (Harris & Harris 2001); see pin-flower. thrum-eyed: "applied to a short-styled dimorphic flower, such as a primrose, the stamens alone being visible in the throat of the corolla" (Jackson), also of the short-styled dimorphic flowers in some species of Galianthe (Rubiaceae). The long-styled counterpart is the pin-flower, q.v.: flos brevistylis, abl. sg. flore brevistyli; flos brevistylus, abl. sg. flore brevistylo.

heterostylus,-a,-um (adj.A), q.v.: heterostylous, i.e. with styles of different length in individuals of the same species and the stamens correlatedly varying in length or position.

Thrum-flower: flos brevistylis, abl. sg. flore brevistyli; thrum, in a heterostylic flower with style[s] shorter than the (longer) stamens.

Pin-flower, “a heterostylic flower with a fairly long style and short stamens” (Harris & Harris 2001): flos longistylis (adj.B), abl. sg. flore longistylidi; cf. thrum.