Schistidium robustum H. Blom 1996

The long, spinulose-denticulate and decurrent awns, strongly sinuose laminal cells, and brown or red-brown, cylindrical capsules with primarily elongate exothecial cells are characteristic features of Schistidium robustum.

Plants in open to compact tufts, olivaceous, sometimes brownish or yellowish. Stems 1-5 cm, central strand distinct. Leaves erect or curved when dry, narrowly ovate-lanceolate to ovate-lanceolate, sharply keeled distally, 1.6-3 mm, 1-stratose, rarely with 2-stratose striae distally; margins recurved to near apex, smooth, 1- or 2-stratose; apices acute, rarely somewhat obtuse; costa usually long-excurrent as a spinulose-denticulate, usually decurrent awn, rarely percurrent, smooth; basal marginal cells quadrate or oblate, trigonous; distal laminal cells short-rectangular, occasionally isodiametric, 8-11 µm wide, strongly sinuose. Sexual condition autoicous. Capsule light brown or red-brown, cylindric to elongate-cylindric, (0.8-)1-1.6 mm, sometimes striated; exothecial cells mostly irregularly shaped, mainly elongate, with numerous isodiametric and, sometimes, a few oblate cells, walls thin-walled to unevenly thickened and somewhat curved, usually trigonous; stomata present; peristome patent to squarrose, sometimes twisted, 300-430 µm, red or orange-red, densely papillose, entire or weakly perforated. Spores 8-11 µm, nearly smooth.

Grimmia robusta Nees & Hornschuch in C. G. D. Nees et al., Bryol. Germ. 2(1): 123, plate 20, fig. 9. 1827

Huuhkajanpaasisammal (Schistidium robustum, (Nees & Hornsch.) H.H. Blom) on lehtisammallaji, joka kuuluu paasisammalten (Schistidium) sukuun ja kivisammalten heimoon (Grimmiaceae). Lajia tavataan maan pohjoisosan lauhkean ja viileän vyöhykkeen mereisillä alueilla. Suomessa laji on harvinainen ja elinvoimainen. Sen kasvupaikkoja tunnetaan 5–6 maakunnasta Varsinais-Suomesta Enontekiön Lappiin. Huuhkajanpaasisammal kasvaa kalkkipitoisilla kallioilla ja lohkareilla, rantakallioilla, metsien kallioilla ja kivillä, joskus myös betonilla.

Schistidium robustum là một loài Rêu trong họ Grimmiaceae. Loài này được (Nees & Hornsch.) H.H. Blom mô tả khoa học đầu tiên năm 1996.