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Genoplesium geminatum M.A.M.Renner & Towle
Family Orchidaceae
Genoplesium geminatum M.A.M.Renner & Towle APNI*

Description: Terrestrial tuberous herb.

Leaf terete, to 21 cm long, 1.0 mm wide, lamina sheathing the scape, linear, free lamina 10–15 mm long and 1.5–2.0 mm wide, ending around 15 mm below the first flower.

Inflorescence 40–60 mm long, bearing 17–30 flowers on a peduncle 20–30 mm long above the leaf; flowers opening in sequence from the base; pedicel and ovary straight, 1.5–2.5 mm long, lengthening with age such that young spikes with newly opened flowers are densely crowded while older spikes with all flowers open and presenting may be openly spaced. Bracts at the base of each flower 1.5 mm long by 1.0 mm wide, with long apex that lays flush on the flower bud and is recurved as the flower opens. Flowers porrect to deflexed, tricoloured, green, cream and dark maroon. Dorsal sepal 4.0 mm long including apex when flattened, 1.3 mm wide triangular-ovate, concave and inflated at medial base, apex shortly attenuate, bearing a small, obovoid, hyaline, stalked gland in bud, but this gland deciduous and shed as the flower opens, gland absent at anthesis. Lateral sepals dark maroon on outer surface, green on inner surface, 4.0 mm long, 1.0 mm wide, linear-lanceolate, widest just above base, concave toward apex sometimes margins overlapping and so tubular, acute, bearing a persistent, hyaline, clavate gland. Petals cream at base grading through maroon to dark maroon around apex, 2.3 mm long, 0.9 mm wide, triangular-falcate, outer surface papillate in distal third, dorsal margin straight in lower third, base not ampliate, then curved through 45° to the apex, margin irregularly crenate to shortly ciliolate in distal half, ventral margin curved at base then arched through around 30° from middle to apex, margin irregularly crenate in outer half, apex long attenuate, hyaline, without gland. Labellum maroon with cream at base either side of callus, 2.0 mm long including apex when flattened, 1.0 mm wide, obovate, widest two thirds from the base, narrowed toward apex which has an acute to acuminate apiculus, margins purple, ciliolate from base to apex, toward the base ciliola are short, papilla-like projections, these projections increase in length with increasing distance above the base and around the apex are turgid, non-flexuous, and up to 250 μm long, callus purple, extending from base into the apex, linear except at the very base where broadens to encompass the labellum width, shallowly channelled above a broad depression at the base, channel extending nearly to the apex, cells of the callus arranged in regular longitudinal rows, in contrast to the adjacent labellum lamina where cells are arranged in radiating rows, and are hyaline in the basal half of the labellum and purple in the upper half, callus surface increasingly papillate from the middle of the labellum toward the apex, papillae formed by prorate surface cells, increasing in length toward the apex, where nearly ciliolate across the labellum surface; attachment narrow, articulated, at apex of column foot. Column 2 mm long not including column foot, 0.8 mm wide; column foot present, thin, falcate, purple, 400 μm long; wings purple, unequally bilobed to 0.5 × of their length, upper lobe around 250 μm long and 100 μm wide, ligulate with an asymmetrically acute apex, margins entire, slightly narrower than lower lobe; lower lobe narrow triangular, apex acuminate, margins and surfaces shortly and closely ciliolate; anther versatile, 0.5 mm long, broad elliptic, with a filiform rostrum whose apex is obtuse; stigma a squat lageniform shape, with a long dorsal projection extending well above the column wings in lateral view, the base rounded, surface ciliolate below dorsal projection. Pollinarium comprising a massulate pollen mass adherent to a white, laciniate ring, a short hamulus and small globose viscidium 0.1 mm wide.

Photo M.A.M. Renner

Photo M.A.M. Renner

Flowering: Summer, from late January to mid February.

Distribution and occurrence: New South Wales. Genoplesium geminatum has been observed at six locations on the North Coast and Central Coast of New South Wales, from Woodford to the immediate south-west and west of Sydney in the south, to Kearsley, Clarence Town, and Myall Lakes National Park north of Newcastle in the north, in addition to the type locality in the Lake Macquarie area.

At the type locality, G. geminatum grew in gravelly orange-brown clay on the edge of a road corridor amongst short sedges and grasses including Themeda.
NSW subdivisions: NC, CC
AVH map***

Genoplesium geminatum can be distinguished from almost all other Genoplesium species by the long acuminate tips to the petals. These long acuminate petal apices are shared with Genoplesium mucronatum, but shorter and equally sharp petal apices occur in other outwardly similar species including Genoplesium laminatum and G. tasmanicum . Genoplesium geminatum can be distinguished from G. mucronatum by the mucronate tip to the floral bract, which is reflexed against the ovary by the opened flower. In G. mucronatum the floral bract is shorter than the ovary and has a rounded to obtuse apex. Other differences between G. geminatum and G. mucronatum are found in the labellum, which is obovate and has projecting cilia around the apex in G. geminatum but is broadly oblong without projecting cilia in G. mucronatum; and in the glands of which there are usually three in the flower buds of G. geminatum (one each on the lateral sepals and on the dorsal sepal), but only two in the buds of G. mucronatum (one . The lateral and dorsal sepals of G. geminatum generally all bear glands, but the gland on the dorsal sepal is either shed, or grows into an acuminus as flowers develop, so that at anthesis only the lateral sepal glands are present. Genoplesium geminatum is illustrated, as G. trifidum, on page 382 of Jones (2021).

APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.
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