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Orobanchaceae

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Broomrape family
Striga bilabiata
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Asterids
Order:
Lamiales
Family:
Orobanchaceae

Orobanchaceae, or the broomrape family, is a family of flowering plants of the order Lamiales, with about 90 genera and more than 2000 species. Many of these genera were formerly included in the family Scrophulariaceae sensu lato. Together they are a monophyletic group, forming a distinct family.

This is a cosmopolitan family, found mainly in temperate Eurasia, North America, South America, parts of Australia, New Zealand and tropical Africa.

Except one genera, (Lindenbergia), all members of this family are holoparasitic or hemiparasitic, annual or perennial herbs or shrubs growing on the roots of their host. The holoparasitic species are completely parasitic, lack chlorophyll, and therefore cannot perform photosynthesis. They may be yellowish, brownish, purplish, or white, i.e. lacking any green color. Their alternate leaves have been reduced to somewhat fleshy, sessile scales that are lanceolate, oblong to ovate. The hemiparasitic species (transferred from Scrophulariaceae) are capable of photosynthesis, and may be facultative or obligate parasites.

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. 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.

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 or birds (e.g. hummingbirds, as in Castilleja).

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, which increases their chance of find a new host.

This family has tremendous economic importance because of the damage caused by genera such as Orobanche and Striga.

Cistanche phelypaea
Bellardia trixago

New genus and species

A species that had not been seen since 1985 was rediscovered in the Sierra Madre del Sur in Mexico. It is an orange-brown, fleshy-stemmed parasitic plant, with a pine cone-shaped dense cluster of flowers and juicy celery-like stalks. According to George Yatskievych, the St. Louis botanist who made the recent find, the plant's formal Latin name will mean "little hermit of Mexico." He expects it will be both a new species and a new genus because "it is so unusual and distinct that it cannot be included in any of the existing genera in the plant family Orobanchaceae". It is a parasite of Hedyosmum mexicanum.[1][2][3]

Genera

Wikimedia Commons has media related to Orobanchaceae.

References

  1. ^ mobot.org, ParasiticPlantRediscovery
  2. ^ blogs.nature.com, Parasitic hermit plant found in Mexico - May 01, 2008
  3. ^ ap.google.com, Scientist rediscovers rare plant unseen since 1985
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