Blepharochilum macphersonii

Evergreen epiphytes that reproduce solely from seed and usually form small clumps. Plants have barely discernible thin short-creeping branched rhizomes anchored by filamentous roots which arise from the base of the pseudobulbs. The pseudobulbs are small, single-noded, crowded and suberect. Each pseudobulb has a single terminal leaf which is longer than wide, from thin (non-Australian) to thick and fleshy and broadly grooved; apex entire. The inflorescences arise from nodes along the rhizome, each with a single flower. The flowers, which last 2-4 days, are relatively small and thin-textured and have no apparent scent.  The lateral sepals are fused to form a synsepalum and the petals are a different shape to the sepals, with hairy margins and an aristate apex. The labellum, which is very obscurely three-lobed, is thin-textured with a large mid-lobe and hairy margins, the hairs towards the base glandular. It is hinged to the apex of the column foot.

Significant Generic Characters

Epiphytic/lithophytic habit; thin rhizomes; filamentous roots; small pseudobulbs; solitary fleshy grooved leaf; single-flowered inflorescence from rhizome nodes; lateral sepals fused to form a synsepalum; petals hairy; labellum tremulous; midlobe large, with hairy margins, some hairs glandular.

Size and Distribution

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distribution map

A genus of about 45 species distributed in Indonesia, New Guinea, Solomon Islands, Vanuatu, New Caledonia and Australia. The genus is particularly well-developed in New Guinea. Two species are endemic in northeastern Queensland more or less between the Big Tableland south of Cooktown (1515' S) and about 2330' S to the north of Rockhampton, above about 450 m alt. State occurence: Queensland.

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Ecology

The Australian species of Blepharochilum grow on shrubs, trees or rocks in highland rainforest and in moist or humid areas of open forest, especially on ridges where there is abundant air movement. The climate is tropical and the majority of rain falls during the summer wet season (December to March), with the remaining months much drier and having sporadic or intermittent rain.

Biology

Pollination: The flowers of the native species of Blepharochilum last 2-4 days and are pollinated by small flies that spend many minutes in the flower probing the labellum. Blepharochilum macphersonii is pollinated by a Midge Fly  - Forcipomyia (Euprojoannisia) sauteri which picks up the pollinarium on the dorsal side of its thorax as it backs out of a flower (Bartareau 1994).

Reproduction: Reproduction in Blepharochilum is solely from seed. Seed dispersal takes 4-6 months after pollination and the capsules develop in an erect position. There is no increase in the length of the peduncle or pedicel during this process. Apomixis is unknown in the genus.

Seasonal Growth: The plants grow during the summer months and for a period after the wet season and are relatively quiescent for the remainder of the year.

Flowering: These orchids flower sporadically with a peak in summer.

Hybrids: Natural hybrids involving species of Blepharochilum are unknown.

Derivation

The generic name Blepharochilum is derived from the Greek blepharon, eyelid and chilum, lip. The labellum has a prominent marginal fringe of hairs that resembles an eyelash.

Botanical Description

Perennial, evergreen, epiphytic or lithophytic herbs, sympodial. Plants glabrous except for trichomes on the labellum. Roots filamentous, produced singly from the base of a pseudobulb. Rhizomes closely appressed to the host, barely discernible, creeping, branched, covered by closely sheathing, imbricate, scarious bracts. Pseudobulbs present, alternate, crowded, erect, single-noded, globose, when young covered by bracts. Trichomes present on the flowers. Leaves subsessile, 1- per shoot, terminal on a pseudobulb, not sheathing at the base, grooved, longer than wide, smooth, from thin (non-Australian) to thick and fleshy, coriaceous; apex entire. Inflorescence arising from a stem node, 1-flowered, erect. Peduncle much longer than the pedicel, with 3-4 closely sheathing, imbricate, scarious sterile bracts at the base.  Floral bract tubular, small, sheathing the base of the pedicel. Pedicel vestigial, straight, merging with the ovary. Ovary short, straight, smooth, merging with the pedicel. Flowers non-resupinate, pedicellate, lasting 2-4 days, usually purplish-red. Perianth segments thin-textured, mostly widely spreading. Dorsal sepal free, subsimilar to the lateral sepals; apex entire, flat.  Lateral sepals fused throughout to form a synsepalum, attached by their bases to the column foot. Petals free, spreading, dissimilar to the sepals; margins hairy; apex aristate. Labellum hinged by a short claw to the apex of the column foot, delicately balanced and tremulous, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina more or less spathulate, very obscurely three-lobed, thin-textured, flat; lateral lobes small, basal, suberect; mid-lobe greatly enlarged; margins hairy, some hairs glandular; apex entire. Callus obscure, consisting of a short shallow central channel. Nectar present. Spur absent. Column lacking free filament and style, short, curved. Column wings present, ventral and with prominent linear apical stelidia which can be notched. Column foot well developed, curved. Pseudospur absent. Anther terminal, incumbent, 2-celled, persistent, basifixed, smooth, rostrate. Pollinarium absent. Pollinia 4 in 2 pairs, triangular, yellow or orange, hard, waxy. Viscidium absent. Rostellum ventral, transverse. Stigma entire, vertical, concave. Capsules large, dehiscent, glabrous, erect, asymmetric; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.

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Taxonomy

Blepharochilum is a segregate genus from Bulbophyllum.

Nomenclature

Blepharochilum M.A.Clem. and D.L. Jones, Orchadian 13(11): 499 (2002).

Type species: Blepharochilum macphersonii M.A.Clem. and D.L.Jones.

Infrageneric Taxa: No infrageneric taxa are currently recognised.

References

Bartareau, T. (1994). Pollination of Bulbophyllum macphersonii Rupp by a Midge Fly (Forcipomyia sauteri). Orchadian 11(6): 255-258.

Clements, M.A. and Jones, D.L. (2002). Nomenclatural changes in the Australian and New Zealand Bulbophyllinae and Eriinae (Orchidaceae). Orchadian 13(11): 498-501.