Family Orobanchaceae Vent.
Сем. CXXI. ВОЛОВОДЕЦОВИ — OROBANCHACEAE VENT. ¹
Fam: Orobanchaceae Vent.
English Name: Broomrapes
Chlorophyll-free annual or perennial herbaceous plants parasitizing on the roots of other plants. Stem simple, rarely branched, usually erect, more or less fleshy. Leaves successive, scaly, fleshy at first. Flowers with bracts, and often with 2 little bracts, collected in a wheat like bract or cluster at the top of the stem, rarely panicle inflorescence or single flowers. Calyx fused of leaflets, bell-shaped or tubular, rarely dissected to the base of 2 (3) entire or two-toothed sections. Corolla tubular, bell-shaped or funnel-shaped, usually bilobed, rarely regular. Upper lip 2-part or entire, lower 3-part, often with a longitudinal fold under the incisions. Stamens 4, free, two-strong (2 by 2 with different long petioles), captured to the corolla tube. Anthers two-nested. The pistil of 2 (3) carpels. The ovary is upper, single-celled. The style at the top with 2-part, rarely with 3 - 4-part or entire stigma. The fruit is a box that opens by 2, rarely 3 seams. Seeds numerous, small. Insect pollinated, propagated by seeds.
Economic significance. Some species, especially of the genus Orobanche - Broomrape or blue wrist, are dangerous weed parasites. They parasitize various crops and cause great damage, greatly reducing yields.
¹ Developed by D. Delipavlov.
From: „Флора на Република България”, том Х, Академично издателство „Проф. Марин Дринов” БАН, София, (1995)
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Orobanchaceae, the broomrapes, is a family of mostly parasitic plants of the order Lamiales, with about 90 genera and more than 2000 species. Many of these genera (e.g., Pedicularis, Rhinanthus, Striga) were formerly included in the family Scrophulariaceae sensu lato. With its new circumscription, Orobanchaceae forms a distinct, monophyletic family. From a phylogenetic perspective, it is defined as the largest crown clade containing Orobanche major and relatives, but neither Paulownia tomentosa nor Phryma leptostachya nor Mazus japonicus.
The Orobanchaceae are annual herbs or perennial herbs or shrubs, and all (except Lindenbergia, Rehmannia and Triaenophora) are parasitic on the roots of other plants—either holoparasitic or hemiparasitic (fully or partly parasitic). The holoparasitic species lack chlorophyll and therefore cannot perform photosynthesis.
The family Orobanchaceae has a cosmopolitan distribution, found mainly in temperate Eurasia, North America, South America, parts of Australia, New Zealand, and tropical Africa. The only exception to its distribution is Antarctica, though some genera may be found in subarctic regions.
Roots and stems
Parasitic plants are attached to their host by means of haustoria, which transfer nutrients from the host to the parasite. Only the hemiparasitic species possess an additional extensive root system referred to as the lateral or side haustoria. In most holoparasitic species there is a swollen mass of short, bulky roots or one big swollen haustorial organ, which may be simple or composite, commonly called the terminal or primary haustorium.
Plants are reduced to short vegetative stems, their alternate leaves are reduced to fleshy, tooth-like scales, and have multicellular hairs interspersed with glandular hairs.
The hemiparasitic species (transferred from Scrophulariaceae) with green leaves are capable of photosynthesis, and may be either facultative or obligate parasites.
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 and they may be yellowish, brownish, purplish, or white. 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 or birds (e.g. hummingbirds, as in Castilleja).
The fruit is a dehiscent, non-fleshy, 1-locular capsule with many very minute endospermic seeds. Fruits of Orobanchaceae are small and abundant and can produce between 10,000–1,000,000 seeds per plant. These are dispersed by the wind over long distances, which increases their chances of finding a new host.
This family has tremendous economic importance because of the damage to crops caused by some species in the genera Orobanche and Striga. They often parasitize cereal crops like sugarcane, maize, millet, sorghum, and other major agricultural crops like cowpea, sunflower, hemp, tomatoes, and legumes. Because of the ubiquitous nature of these particular parasites in developing countries, it is estimated to affect the livelihood of over 100 million people, killing 20 to 100 percent of crops depending on infestation.
Some genera, especially Cistanche and Conopholis, are threatened by human activity, including habitat destruction and over-harvesting of both the plants and their hosts.
Research for this plant family can often be difficult due to its permit requirements for collection, travel, and research.
From Wikipedia, the free encyclopedia
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Distribution in Bulgaria: (Conspectus of the Bulgarian Vascular Flora) = conspectus&gs_l= Zlc.
References: „Флора на Република България”, том Х, Академично издателство „Проф. Марин Дринов” БАН, София, (1995), Wikipedia, the free encyclopedia
Genus Orobanche L. - Broomrape or Broom-rape
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