A Grammatical Dictionary of Botanical Latin

hygroscopic, hygrometric, “susceptible of extending or shrinking on the application or removal of water or vapor” (Jackson); changing form or position with changes in humidity or moisture, readily absorbing moisture and then changing form or poise by expansion (Stearn), as in the peristome teeth and setae of mosses: hygrometricus,-a,-um (adj.A), hygroscopicus,-a,-um (adj.A);

- cruribus lineari-subulatis, apice subulatis fragilibus, valde hygroscopicis, with the peristome teeth [lit. ‘legs’] linear-subulate, subulate at the apex, fragile, strongly hygroscopic.

- PEDVNCVLVS dilute viridis, circa maturitatem in fuscellum vergens colorem (Hedw.), et valde tortilis, tempestate sicca; hinc hygrometricus (Hedw.), the pedunculus [i.e. the seta] is a diluted green, around maturity approaching a light fuscous color, and strongly twisting in dry weather, hence hygrometric.

- dentes peristomii humiditate incurvi et involuli, siccitate (in theca supra matura) reflexi thecae adpressi vel tortuoso-defluentes summopere hygroscopici, the peristome teeth in humidity incurved and involute, in dryness (in the theca matura above) reflexed, appressed to the theca or tortuose-descending, exceedingly hygroscopic.

- peristomio saepe longissimo hygroscopico, with the peristome often very long, hygroscopic.

- fili rufescentibus pluribus inarticulatis percurrentibus, subincurvi haud hygroscopici firmi, with the threads reddish, many, not articulated, percurrent, nearly incurved, not hygroscopic, firm.

Cellula,-ae (s.f.I) hygroscopica: “certain cells in the leaves of grasses which cause them to alter in shape in dry weather, known also as bulliform cells” (Jackson).

NOTE: hygroscopicitas,-atis (s.f.III), abl. sg. hygroscopicitate: “the property of extending or shrinking upon the application or removal of water” (Lindley).

Funaria hygroscopica Hedw., a moss, “... has a long seta which twists and curls with changes in humidity, thus accounting for the specific epithet” (C&A).