Orobanchaceae

From Wikipedia, the free encyclopedia

Broomrape family

Erinus alpinus

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Lamiales
Family:	Orobanchaceae

Genera

See text.

Orobanchaceae , or the broomrape family, is a family of flowering plants of the order Lamiales, with about 25 genera and more than 200 species. Many of these genera were formerly included in the family Scrophulariaceae s.l. Together they are a monophyletic group, forming a distinct family.

This is a cosmopolitan family, found mainly in temperate Eurasia, except South America, parts of Australia and New Zealand. There are only a few tropical African and American species.

These plants are holoparasitic or hemiparasitic, annual or perennial herbs growing on the roots of their host. The holoparasitic species are completely parasitic, lack chlorophyll, and cannot perform photosynthesis. The hemiparasitic species (transferred from Scrophulariaceae) are capable of photosynthesis, while also being parasitic.

Only few species possess an extensive root system. In most species there is a swollen mass of short, bulky roots or one big swollen organ, simple or composite. The roots are attached to their host by means of hooked haustoria, which transfer nutrients from the host to the parasite.

They have reduced, somewhat fleshy, scaly, sessile leaves. These simple, lanceolate, oblong to ovate scales are small and alternate.

The hermaphroditic flowers are bilaterally symmetrical and grow either in racemes or spikes or singly at the apex of the slender stem. The tubular calyx is formed by 2-5 united sepals. There are five united, bilabiate petals forming the corolla. The upper lip is two-lobed, the lower lip is three-lobed. There are two long and two short stamens on slender filaments, inserted below the middle, or at the base of the corolla tube, alternating with the lobes of the tube. A fifth stamen is either sterile or lacking completely. The anthers dehisce via longitudinal slits. The pistil is one-celled. The ovary is superior. The flowers are pollinated by insects.

The fruit is a dehiscent, non-fleshy, 1-locular capsule with many very minute endospermic seeds. These are dispersed by the wind over long distances, increasing their chances to find a new host.

The plants may be yellowish, brownish, purplish, or white but lack any green color, except the hemiparasitic parasites.

This family has no economic importance, except for some species being harmful to feed crops.