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Acianthinae_species
Acianthus exsertus R. Br.
Nomenclature
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Genus: Acianthus
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Synonyms: 1
SUMMARY
Plant: Erect herb 6-26 cm tall.
Stem: Straight, terete, 0.7-8 cm long, green or greenish red, glabrous.
Cataphyll: Sheathing, tubular, 4-7 mm long, membranaceous, 1-nerved, somewhat expanded distally, the apex very broadly acute.
Leaf: Sessile, entire or rarely weakly 3-lobed, broadly ovate, or sometimes suborbicular-ovate, 1.2-5.5 cm long, 1-4.8 cm broad, dark green above, reddish green or rarely pale green beneath, the base deeply cordate with closely approximate or more frequently weakly divergent basal lobes, the apex acuminate or rarely subacute, and frequently minutely apiculate, the margin entire, weakly undulate, or sometimes minutely crenulate.
Peduncle: 1.5-14 cm long.
Inflorescence: Slender, 3-24 cm tall, laxly to subdensely, (1-) 3- to 20-flowered.
Bracts: Ovate, suborbicular-ovate, ovate-elliptic, or obovate-elliptic, 2-8 (-12) mm long, 1.3-5 (-10) mm broad, 3- to 5-nerved, dark green, with a few scattered, oblong-elliptic idioblasts distally, the base broadly rounded, cuneate, or rarely briefly cordate, the apex gradually to abruptly acuminate.
Ovary: Briefly pedicellate, cylindrical-clavate, 4.5-8 mm long, weakly 6-ribbed.
Flowers: Ascending, the outer perianth segments somewhat translucent, pale greenish red to greenish purple, sometimes with reddish markings along the nerves and at the tips, or rarely pale green, the labellum pale green, the lateral margins and apex suffused with pinkish red or dark reddish purple, the column greenish white.
Dorsal Sepal: Broadly spreading, oblong-obovate, elliptic- obovate, or sometimes elliptic, 5-10 mm long, 2-4 mm broad, 3-nerved, slightly cucullate distally, angustate at base, abruptly acuminate and strongly apiculate at apex, the apicule setiform or subclavate, 1-2.5 mm long.
Lateral Sepals: Slightly reclined, weakly appressed to labellum, frequently a little indexed and weakly divergent from each other distally, linear-oblanceolate or linear-attenuate, 6-9 mm long, 0.5-0.8 mm broad, 1-nerved, narrowly acute and manifestly apiculate at apex, the apicule setiform or subclavate, 1-4 mm long.
Lateral Petals: Strongly retrorse and frequently weakly ascending, lanceolate or ovate, slightly oblique, 2-5 mm long, 0.8-1.5 mm broad, 1-nerved, very gradually acuminate at apex.
Labellum: Weakly to strongly reclined, briefly clawed, very weakly sigmoid, entire, 3-5 mm long, 1.5-3 mm broad, 3-nerved, the blade oblong-ovate or oblong-lanceolate, somewhat sulcate proximally, weakly porcate laterally, broadly cuneate at base, somewhat depressed and abruptly acuminate or acute at apex, the lateral margins gradually becoming weakly revolute medially, entire, the disk with 2 large calli at base, very finely reticulate throughout a broad longitudinal medial band, otherwise unappendaged or sometimes very weakly papillose distally, the calli partially embracing column base, erect, clavate-falcate, gradually increasing in height distally and weakly confluent with each other apically.
Column: Arcuate, terete, 2.3-3.5 mm long, unappendaged, prominently gibbous at base, strongly dilated at apex; anther locules suborbicular, 0.6-0.8 mm across; pollinia strongly 2-lobed, the lobes more or less clavate or pyriform, relatively firm, unequal, 0.3-0.5 mm long, the viscidia 2, broadly ovate or transversely ovate, ca. 0.2 mm across; rostellum porrect, relatively long, the anterior margin weakly tri-denticulate; stigma small, suborbicular, shallowly recessed.
Capsule: Oblong-obovoid or oblong-ellipsoid, 7-12 mm long, 2.5-3.5 mm in diameter.
Type: AUSTRALIA. Port Jackson: North Rocks, May 1804 (fl), R. Brown s. n. (lectoype designated by Clements in Austral. Orchid Res. 1: 9. 1989: bm!; isolectotypes: bm!, le)