Eulophia R.Br.

Distribution

As it is presently understood, Eulophia comprises some 230 species (Thomas 1998). It is most diverse in tropical and southern Africa, with substantial diversity elsewhere only in Madagascar and tropical Asia. About 40 species are found in Asia, mostly tropical in distribution, but the range of E. dabia (D.Don) Hochr. extends into temperate central Asia in Turkestan, Afghanistan, and western China. A few Asiatic species are found in northeastern Australia and southwestern Pacific islands. Of these, E. spectabilis (Dennst.) Suresh is autogamous in the region, and E. zollingeri (Rchb.f.) J.J.Sm. is holomycotrophic. Peloric forms of E. pulchra (Thouars) Lindl. are common in the Pacific portion of its distribution.
Eulophia alta (L.) Fawc. & Rendle is the only species reliably reported from both sides of the Atlantic, in tropical America, where it is widespread from Florida and the Caribbean south to Brazil, and in tropical Africa. It is one of only two species in the genus found in the Americas.
Many species in the genus are widespread. For example, both E. petersii (Rchb.f.) Rchb.f. and E. speciosa (R.Br. ex Lindl.) Bolus range from the Arabian Peninsula to South Africa. Eulophia streptopetala is found from Ethiopia to the Cape. Eulophia guineensis ranges from Sierra Leone in western Africa east to Ethiopia and south to Zimbabwe. Eulophia livingstoniana (Rchb.f.) Schltr., E. cucullata (Sw.) Steud., and E. tuberculata Bolus are all found in Africa and Madagascar. Eulophia pulchra is even more widespread from tropical Africa and Madagascar across tropical Asia and the Malay Archipelago to New Guinea, the Philippines, and southwestern Pacific islands. The broad latitudinal spread of some species, e.g., E. cucullata and E. streptopetala, may be linked to polyploidy. (PC).

Ecology

The centre of diversity of the genus is Africa where Eulophia species can be found in a wide variety of habitats from the margins of deserts to permanent marshes and from dry savanna woodlands to wet tropical forests. Such adaptability may be explained, at least in part, by their storage organs, whether fleshy rhizomes, tubers or pseudobulbs, that allow them to survive extended periods of drought. Indeed, within their specific environments, many species have widespread ranges, which may be one consequence of polyploidy noted within some species, such as E. cucullata and E. streptopetala (Hall 1965; Poggio et al. 1986).
The succulent Eulophia petersii, resembling a Sansevieria Thunb. in its habit with prominent conical to fusiform pseudobulbs and two or three succulent, leathery leaves, is drought-resistant. It is one of the few orchids found in arid, semi-desert habitats in northeastern Africa, the southwestern Arabian Peninsula, and throughout tropical east Africa.
Seasonal grasslands and savanna woodland (the latter referred to as miombo in south-central Africa), running west across to east Africa and south to south-central Africa, are the habitats of many species, including a number of holomycotrophic (often termed ‘saprophytic’) and semi-holomycotrophic species. The former, such as E. richardsiae P.J.Cribb, lack green leaves and appear only when flowering. The latter, including E. longisepala Rendle, E. subsaprophytica Schltr., and E. paradoxa, flower when leafless, but short leaves appear after the infl orescence has died or set seed. The holomycotrophic species have swollen subterranean rhizomes and no roots. The semi-holomycotrophic species usually have subterranean chains of pseudobulbs of various shapes and sizes as well as true roots.
Leafy species are common in wetter habitats. Eulophia horsfallii (Bateman) Summerh. and its allies are found in evergreen montane forests, often close to running water. Their pseudobulbs are mostly subterranean and often form chains. Their leaves are noticeably pleated and often large and broad. Tropical African E. euglossa (Rchb.f.) Rchb.f., E. gracilis Lindl., and E. guineensis occur in deep shade in evergreen forests in brown soils on ironstone. The last will grow on rocks in hollows with a little soil and humus in which the roots can elongate. A leafless exception is the holomycotrophic species, E. galeoloides Kränzl., which grows from a rootless tuber in leaf-litter and deep shade of evergreen forests.
Many species are found in grasslands in eastern and southcentral Africa, especially the brightly coloured species allied to E. euantha, E. thomsonii, and E. walleri. Others prefer a wetter habitat, namely seasonally wet grasslands, called dambos in south-central Africa and vleis in South Africa. Eulophia cucullata, E. latilabris Summerh., E. speciosa, and allied species have chains of subterranean pseudobulbs but relatively narrow leaves. These species can be widespread, found throughout tropical and into southern Africa. Eulophia speciosa ranges from western Africa into south-west of the Arabian Peninsula and south to South Africa. A few species, including E. cucullata, E. hians Spreng. var. nutans (Sonder) S.Thomas, E. livingstoneana, and E. clitellifera, are found in both Africa and Madagascar, but most Madagascan species are endemic. A few species grow in permanent swamps and marshes, notably E. caricifolia (Rchb.f.) Summerh. and its allies, which have elongated cylindrical rhizomes, not unlike Typha L. (Typhaceae) and other swamp plants. Only two species, E. alta and E. ecristata Ames, are found in the tropical Americas. The former has an amphi-Atlantic distribution, as it is also found in tropical Africa. Africa and Madagascar do not share any species with Asia and Australasia. Asia has more than 50 species, most in grassland, woodland or forest. Eulophia spectabilis, found from India and China to Fiji, is one of the most widespread of all species. Likewise, the holomycotrophic E. zollingeri ranges from China and Japan to northern Australia. Both species may be autogamous in parts of their ranges. (PC).

General Description

Terrestrial or less commonly lithophytic herbs, chlorophyll deficient (heteromycotrophic) or holomycotrophic. Roots basal, often with a well-defined white velamen. Perennating organ stem-like or pseudobulbous if above ground, rhizomatous or tuberous if subterranean, cylindrical, fusiform, conical or ovoid, homoblastic. Leaves linear, lanceolate, ovate or elliptic, acute to acuminate, coriaceous, articulate or not to a sheathing base; rarely lacking chlorophyll and scale-like in holomycotrophic species. Inflorescence lateral, simple or rarely branching; bracts persistent. Flowers green or brown to coloured, occasionally bicoloured. Dorsal sepal free, oblong, elliptic, lanceolate or oblanceolate, reflexed, erect or porrect; lateral sepals oblique at base and decurrent on column foot, otherwise similar to dorsal sepal. Petals free, similar or dissimilar to sepals, often larger, broader and distinctively coloured compared to sepals. Labellum free to base or fused to base of column, trilobed, spurred at base, lateral lobes free or fused to base of column, midlobe flat or convex; callus two- or three-ridged or papillose. Column usually with a foot; pollinia two, globose, stipe solitary, triangular to oblong, viscidium oblong, elliptic to lunate. Ovary cylindrical, grooved. (PC).

Small, medium or large terrestrial or rarely lithophytic herbs; roots slender to stout, basal or adventitious, often with a well-defined velamen. Perennating organs stem-like, pseudobulbous or tuber-like, above the ground or more commonly underground, conical, cylindrical or irregular in shape, several-noded. Leaves usually present and green but in some species much reduced, scale-like and brown or buff; green leaves 1–many, thin-textured to fleshy or coriaceous, with or without prominent longitudinal veins, linear, lanceolate, ovate or elliptic, sheathing at the base; scale leaves when present sheathing. Inflorescences basal, laxly to subdensely many-flowered, usually racemose, rarely branching. Flowers small to large, sometimes showy and brightly coloured. Sepals and petals similar or with the petals much broader, free to base or with the lateral sepals fused at the base to the column-foot. Lip 3-lobed, spurred at the base, usually with a callus of ridges and/or papillae on upper surface. Column short to long, with or without a column-foot; anther-cap entire or 2-lobed at the apex; pollinia 2, subglobose; stipes solitary, triangular to oblong; viscidium oblong, elliptic or lunate.

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Terrestrial or lithophytic herbs from perennial rhizome with roots mostly covered by a distinct white velamen; rhizome or above-ground stem often condensed to form several-noded tuber-like or pseudobulbous storing organs

Morphology Leaves

Leaves soft and thin to fleshy and coriaceous from flowering or separate shoot

Morphology Reproductive morphology Inflorescences

Inflorescence a lax to rather dense many-flowered raceme or panicle, with small to large, rather showy flowers

Morphology Reproductive morphology Flowers Tepal

Tepals entire; sepals greenish and calyx-like or brightly coloured, corolla-like and similar to the petals

Morphology Reproductive morphology Flowers Corolla

Lip 3-lobed, shortly spurred and with ridges and papillae on upper surface; spur with few exceptions conical, nectarless

Morphology Reproductive morphology Flowers Column

Column mostly rather long; pollinia 2, subglobose, waxy.

Distribution

A genus with about 200 species, widespread in tropical and subtropical areas.

Note

The existence of two Somali collections of E. clavicornis Lindl. var. nutans (Sond.) A. V. Hall was mentioned by Cribb in Kew Bull. 42: 462–463 (1987), but the occurrence of this species in Somalia has not been substantiated and it is omitted here.

Orchidaceae, I. la Croix & P.J. Cribb. Flora Zambesiaca 11:2. 1998

Morphology General Habit

Small to large terrestrial herbs, sometimes saprophytic; roots slender to stout, often with a velamen.

Vegetative Multiplication Pseudobulbs

Perennating organs usually subterranean but sometimes above ground, and pseudobulbous, conical, cylindrical or irregularly shaped, with several nodes.

Morphology Leaves

Leaves usually present and thin-textured to fleshy or coriaceous, but in some species reduced and scale-like, brown or yellow-buff.

Morphology Reproductive morphology Inflorescences

Inflorescences basal, usually many-flowered, usually simple but occasionally branched.

Morphology Reproductive morphology Flowers

Flowers small to large, often showy and brightly coloured.

Morphology Reproductive morphology Flowers Calyx

Sepals and petals either similar, or the petals much broader; free to the base or with the lateral sepals fused at the base to the column foot.

Morphology Reproductive morphology Flowers Labellum

Lip 3-lobed, usually with a callus of ridges and/or papillae; spurred at the base, the spur sometimes obscure and sac-like.

Morphology Reproductive morphology Flowers Column

Column long or short, with or without a foot; anther cap entire or bilobed at the apex; pollinia 2, subglobose; stipes 1, triangular to oblong; viscidium oblong, elliptic or lunate.

Orchidaceae, I. la Croix & P.J. Cribb. Flora Zambesiaca 11:2. 1998

Morphology General Habit

Terrestrial, sympodial herbs.

Morphology Stem

Stem subterranean, made up of a chain of fleshy, lobed tubers.

Morphology Leaves

Leaves 1–3, petiolate, linear-lanceolate, plicate, enclosed in sheaths towards the base.

Morphology Reproductive morphology Inflorescences Scape

Scape arising with leaves from the current year’s growth, covered with subscarious tubular sheaths.

Morphology Reproductive morphology Inflorescences

Inflorescence a short terminal raceme, usually with conspicuous bracts exceeding the flowers.

Morphology Reproductive morphology Flowers

Flowers medium sized, resupinate or nonresupinate.

Morphology Reproductive morphology Flowers Calyx

Sepals and petals free, spreading, the petals usually slightly shorter than the sepals but otherwise similar.

Morphology Reproductive morphology Flowers Labellum

Lip lacking a claw, usually 3-lobed but sometimes entire, not spurred or saccate, flat, with either the disk entirely tuberculate or the nerves tuberculate, verrucose or keeled; mid-vein of side lobes often raised into a ridge at the base.

Morphology Reproductive morphology Flowers Column

Column short, broad, curved, with 2 auricles at the base, lacking a foot or with a very rudimentary foot; anther terminal, ovate, obtuse, apiculate, unilocular; pollinia 2, subglobose; stipes 1, short and broad; viscidium 1, scale-like.

Orchidaceae, V. S. Summerhayes. Flora of Tropical East Africa. 1968

Morphology General Habit

Terrestrial, sympodial herbs

Morphology Stem

Subterranean stem composed of a series of lobed fleshy tubers; aerial stem very short

Morphology Leaves

Leaves 1–3, linear-lanceolate, long-petiolate, plicate, enclosed in sheaths towards base, arising with scape from the current year’s growth

Morphology Reproductive morphology Inflorescences Scape

Scape erect, covered with subscarious, tubular sheaths

Morphology Reproductive morphology Inflorescences

Inflorescence a several-flowered, short, dense, rarely elongated and lax, terminal raceme; bracts usually conspicuous, long, narrow, rarely broad, scarious, often exceeding the flowers

Morphology Reproductive morphology Flowers

Flowers resupinate or non-resupinate, medium-sized

Morphology Reproductive morphology Flowers Perianth

Sepals and petals similar, free, usually spreading, the petals usually shorter than the sepals

Morphology Reproductive morphology Flowers Labellum

Lip sessile, 3-lobed, rarely entire, neither spurred, saccate nor clawed, flat, never concave, mid-lobe larger than side lobes, apex usually recurved, disc either entirely tuberculate or the nerves variously tuberculate, verruculose or lacerately keeled, median nerve of the side lobes often raised and ridge-like at the base

Morphology Reproductive morphology Flowers Column

Column very short, rarely elongated, broad, curved and biauriculate at the base, the 2 auricles merging with the base of the lip, wings absent, foot absent or very rarely rudimentary, ± horizontal; anther terminal, ovate, obtuse, apiculate, unilocular; pollinia 2, subglobose, united on a short broad stipes; viscidium large, scale-like.