Phalaenopsis rosenstromii

Porrect epiphytes with numerous thick roots and short fibrous leafy stems, unbranched or sparsely branched from near the base. The thin, fleshy, crowded leaves, arranged in 2 ranks, are often widest above the middle. Inflorescences are long arching racemes or panicles with numerous moderately small to large showy flowers. The flowers, which are long-lasting, have broader petals than sepals and a 3-lobed labellum fixed to the apex of the column foot. The apex of the midlobe often has a pair of long thin appendages known as “antennae”. The column is long with a prominent column foot.

Significant Generic Characters

Epiphytic orchids; plants small to large, usually porrect; roots numerous, thick, sometimes forming a buttress; stems short, fibrous, unbranched or sparsely branched from the base; leaves flat, crowded, arranged in 2 ranks , often widening distally, thin, fleshy; inflorescence racemose or paniculate, multiflowered; flowers moderately small to large, lasting many days; labellum firmly attached to the apex of the column foot; lamina 3-lobed, without a spur; lateral lobes large, erect or incurved; column long, with a long foot; pollinia 2, sessile on a stipe.

Size and Distribution

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A genus of about 35 species distributed in India, China, Malaysia, Philippines, Indonesia, New Guinea and Australia where there is 1 endemic species, Phalaenopsis rosenstromii,  distributed sporadically between the Iron Range (12º38’ S) and Mt Spec near Townsville (about 19º S). State occurrence: Queensland.

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Phalaenopsis rosenstromii grows on trees in rainforest at low to moderate altitudes, usually in sheltered humid situations where there is abundant air movement, such as near waterfalls and overhanging streams. Occasional plants are found on rocks. 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.


Pollination: The flowers of Phalaenopsis rosenstromii are very long lasting. They are insect-pollinated but the vector is unknown.

Reproduction: Reproduction in Phalaenopsis is solely from seed. Seed dispersal takes 10-12 months after pollination and the capsules develop in a porrect position. Apomixis is unknown in the genus.

Seasonal Growth: Phalaenopsis plants grow mainly during the spring and summer months and are relatively quiescent for the remainder of the year.

Flowering: Phalaenopsis rosenstromii flowers mainly in summer and autumn.

Hybrids: Natural hybrids involving Phalaenopsis rosenstromii are unknown.


Phalaenopsis is derived from the Greek phalaina, moth and –opsis, appearance, the flowers of some species resemble large moths.

Botanical Description

Perennial, evergreen, epiphytic or lithophytic herbs, monopodial. Roots numerous, thick, elongate, much branched, mainly adherent, sometimes forming a buttress. Plants small to moderately large, unbranched or sparsely branched from the base, porrect. Stem short to moderately long, fibrous, leafy throughout. Pseudobulbs absent. Trichomes absent. Leaves lasting several seasons, flat, distichous, sessile, crowded, spreading widely or drooping, longer than wide, often widest distally, thin textured, fleshy; base sheathing the stem, imbricate with its neighbour, persistent after leaf abscission; margins entire or undulate; apex unequally emarginate. Inflorescence lateral, racemose or paniculate, arcuate, multiflowered. Peduncle shorter or similar to the rhachisRhachis straight. Floral bracts small, scarious, partly sheathing the base of the pedicel. Pedicel short to moderately long, merging with the ovary. Ovary short, straight. Flowers resupinate, small to large, opening sequentially, stalked, lasting many days, white, cream, yellowish or pinkish. Perianth segments relatively thin-textured, spreading, often broadest distally. Dorsal sepal free, subsimilar or different to the lateral sepals, not cucullateLateral sepals free, subsimilar or different to the dorsal sepal, usually flanking the labellum. Petals free, often broader than the sepals. Labellum stiffly attached to the apex of the column foot, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina 3-lobed; lateral lobes large, erect or incurved; midlobe long, porrect, the apex sometimes adorned with 2 long filiform “antennae”. Spur absent. Callus consisting of one or more large, fleshy, entire, bifid or grooved, basal protruberances. Nectar unknown. Column long, porrect from the apex of the ovary, lacking free filament and style, fleshy, straight. Column wings small, lateral. Column foot long, at right angles to the column. Pseudospur absent. Anther terminal, incumbent, 2-celled, persistent, smooth, with a large decurved rostrum. Pollinarium present. Pollinia 2, orange, hard, waxy, sessile. Stipe broad, often spathulate. Viscidium large, at an angle to the stipe. Rostellum broad, deeply bifid, sometimes the arms deflexed. Stigma entire, concave. Capsules dehiscent, elongate, glabrous, porrect; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.

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Within the Vandeae, Phalaenopsis is distinguished by; small to large plants; thin-textured, fleshy, leaves that often widen distally; racemose or paniculate inflorescences; petals often broader than the sepals; labellum fixed to the apex of the column foot; lamina 3-lobed, without a spur; lateral lobes large; midlobe projecting, often with 2 terminal filiform “antennae”; column long, with a long foot and, 2 sessile pollinia.


Phalaenopsis rosenstromii has suffered severe population pressure from illegal collection with the plants stripped from many well-known sites.


Phalaenopsis Blume, Bijdr. 7:  294 (1825). Type species: Phalaenopsis amabilis Blume.

Infrageneric Taxa: No infrageneric taxa are currently recognised.


Dockrill, A.W. (1967). Australasian Sarcanthinae. The Australasian Native Orchid Society, Sydney.

Dockrill, A.W. (1969). Australian Indigenous Orchids. Volume 1. The Society for Growing Australian Plants, Halstead Press, Sydney.

Dockrill, A.W. (1992). Australian Indigenous Orchids. Volume 1 & 2. Surrey Beatty & Sons in association with The Society for Growing Australian Plants, Chipping Norton, NSW.

Garay, L. (1972). On the systematics of the monopodial orchids. Bot. Mus. Leafl. Harv. Uni. 23(4): 149-212.

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