Cyrtostylis huegelii
Plant: Erect herb 8-35 cm tall.
Stem: Straight, terete, 0.5-3.5 cm long, pale green, glabrous.
Cataphyll: Weakly clasping, broadly ovate, 3-9 mm long, membranaceous, 1-nerved, the apex gradually acuminate.
Leaf: Sessile, often appressed to ground, entire, broadly ovate-elliptic to suborbicular, 2.4-6 (-8) cm long, 2.5- 5 cm broad, dark green above, pale greenish white beneath, the base usually deeply cordate with strongly imbricate basal lobes, the apex broadly subacute to rounded, the margin entire.
Peduncle: 6-20 cm long.
Inflorescence: Slender, 12-32 cm tall, laxly (2-) 5- to 15-flowered.
Bracts: Ovate to ovate-elliptic, 4-8 mm long, 1.5-4 (- 5) mm broad, 1- to 3-nerved, dark green, with a few scattered, linear-elliptic idioblasts distally, the base cuneate, the apex gradually acuminate.
Ovary: Pedicellate, cylindrical-clavate, 5-9 mm long, 6-ribbed.
Flowers: Erect, the outer perianth segments and column pale green or green suffused with brown, the labellum maroon.
Dorsal Sepal: Erect, a little incurved distally, ligulate, 12- 13.5 mm long, 2-2.3 mm broad, 3-nerved, slightly channeled, abruptly acuminate or subacute at apex.
Lateral Sepals: Porrect to weakly reclined, weakly appressed to labellum, hardly or not divergent from each other, linear-ligulate, 9-10 mm long, 0.8-1.3 mm broad, incompletely 3-nerved, weakly channeled, narrowly subacute at apex.
Lateral Petals: Broadly spreading to weakly reflexed, frequently a little incurved toward labellum distally, linear-attenuate, 10-11.5 mm long, 0.5-0.8 mm broad, 1-nerved, narrowly acute at apex.
Labellum: Initially ascending and weakly channeled for a short distance, distally moderately geniculately reflexed and obliquely reclined, sessile, entire, narrowly oblong, 8-11 mm long, 2.5-3 mm broad, finely 9- to 13-nerved, the base truncate or very briefly cordate, weakly embracing the column, the apex acute or sometimes abruptly acuminate, the lateral margins weakly incurved proximally, gradually becoming a little revolute and slightly undulate or crenulate distally, the disk with a pair of prominent basal calli, laterally flanked by 2 small, transverse, oblong-pulvinate thickenings and longitudinally carinate distally, the calli initially weakly raised, ridge-like, ultimately abruptly expanded, erect, aliform, strongly joined proximally by a transverse crest, slightly inflexed and a little incrassate at the tips, the carinae 2, weakly raised, gradually diminishing in height toward the apex of disk, the upper surface of disk between the aliform portions of calli with a weakly marginate, concave depression, the portion distal to depression very finely reticulate throughout a medial, linear-ligulate region.
Column: Slender, semiterete, 5-6 mm long, weakly alate along lateral margins of ventral surface throughout, the base slightly dilated and briefly auriculate laterally, the distal portion strongly incurved, prominently gibbous anteriorly at base of stigma and a little dilated at apex, the lateral wings rather abruptly dilated near stigma; anther locules reniform, 0.8-1.2 mm across; pollinia subreniform, slightly unequal, somewhat compressed laterally, mealy, 0.8-1 mm long, the viscidia 2, porrect, transversely elliptic, ca. 0.2 mm across; rostellum relatively long, transverse, the anterior margin very abruptly acuminate; stigma large, transversely elliptical, very deeply recessed.
Capsule: Ellipsoid or oblong-ellipsoid, 12-15 mm long, ca. 4 mm in diameter.
Type: AUSTRALIA. Rottnest Island, Aug. 22, 1839(H), Preiss 2204 (holotype: hbg (photo ny); ISOTYPES: G, LE (photo NY), M, MEL, Mo! Pi, W)
Distribution: Endemic to and restricted to coastal regions of Western Australia from just south of Kalbarii to Israelite Bay.
Ecology: The species only occurs in sheltered localities as part of the herbaceous layer under stands of dense forest, or within shrub thickets. Near the coast it sometimes forms dense colonies in the protected hollows of sand dunes or up against the trunks of fallen trees.
Elevation: From near sea level to approximately 300 m.
Phenology: Flowering July through September.
Similar Species: Acianthus huegelii is very similar in appearance to A. reniformis (R. Br.) Schltr., but is distinguished by its light colored flowers and narrowly oblong labellum, which is often distinctly acute. In addition, the disk has a distinct concave depression between the distal appendages of the basal calli, and the column has a prominent anterior swelling at the base of the stigma. Acianthus huegelii is sympatric with A. robsta and A. tenuissimus Nicholls & Goadby, and is reported to form sporadic hybrids with the former (as Cyrtostylis robusta D. L. Jones & Clements) (Jones, 1988).