Helixanthera

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Helixanthera

Description

Aerial stem-parasitic shrubs, sometimes with epicortical runners bearing secondary haustoria, or rarely (not in Malesia) terrestrial root parasites. Leaves opposite, scattered or sometimes crowded to false whorls. Inflorescence a simple raceme or spike; bracts single under each flower. Fruit ovoid.

Distribution

Asia-Tropical:, Borneopresent; Jawa (Jawapresent); Malaya (Peninsular Malaysiapresent); Philippines (Philippinespresent); Sulawesi (Sulawesipresent); Sumatera (Sumaterapresent) Tropical Africa: present southern Asia: present
About 35 species in tropical Africa, southern Asia and Malesia. In Malesia 11 species with their diversity centred on Peninsular Malaysia, Sumatra and Borneo, and reaching the Philippines, Celebes and Java.

Ecology

Host specificity is low; some species are aggressive, with broad host ranges, often occurring on cultivated trees.

Morphology

Several groups of species in Helixanthera are defined by differences especially in the form of the ovary, corolla and style. The ovary may be of the shortly cylindric or urceolate form typical of the family generally, or greatly elongated. The corolla in bud may be slightly curved, gradually tapered and acute (described as 'beak-like' by Danser) or regular; in the latter case it may be campanulate and winged below or not. The style may reach to the top of the flower, as in most loranths, or only to near the base of the anthers; it may be simple or articulate, with lower and upper segments which may differ in width and angularity.

Taxonomy

Combinations of the differences mentioned above have provided the basis for recognition of segregate genera, especially by Van Tieghem. Danser (1929, 1933) considered that there was little to justify the acceptance of a large number of small genera based on these differences, and his view is followed here. However, circumscription of a single diverse genus Helixanthera presents some difficulties in distinction of the closely related genus Loranthus (see discussion there).

Citation

Danser - in Bull. Jard. Bot. Buitenzorg. 1931: 368