Get complete information on Family Orchideae

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Habit:

Terrestrial, Saprophytes, Bulbophyllum is an epiphytic climber.

Root:

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Adventitious roots which are of three kinds normal roots, tuberous roots and aerial roots. The latter again are of three types–clinging roots which are negatively geotropic and finally aerial roots which are most important, hand downwards and are branched. These possess velamen thickenings which are meant to absorb moisture.

Stem:

More or less elongate, solitary composed of discrete pseudobubs, jointed and made up of elongated pseudobubs, leafy, tuber or rhizome, sealy bulb in Dendrophylax and very short in Ornithochilus. Stem of an epiphytic form is generally a pseudobulb. Saprophytic types have no chlorophyll.

Leaf:

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Foliage leaves are lacking in Dendrophylax radical leaves in Orchis and Pogonia, hair like in Bulbophyllum, solitary or in pairs, in Pholidota, almost sessile, exstipulate, leaf base sheathing, and unicostate parallel venation.

Inflorescence:

Usually racemose which may be short lined or perennial.

Flower:

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Pedicellate or sessile, usually bracteate, hermaphrodite, zygomorphic, epigynous, incomplete, trimerous. Flowers are generally large, showy and quite attractive, in some cases like Pleurothalis these may be small and inconspicuous.

Perianth:

Tepals 6 in two whorls of 3 each. Free or slightly united, 3 outer more or less similar (2 lateral sometimes united forming a short or long sac or spur like base which is also called mentum). Three inner tepals dissimilar. (2 lateral similar, one medium is of different shape, variable in colour and is called lip or labellum). Labellum is bigger than others of the inner whorl. A spur develops partly from lip and partly from axis in Orchis where it store honey.

Androecium:

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Stamens usually one (two in case of cypripedium). When it is one it is of the outer whorl and two of the inner whorl are staminodes, free or adnate. Stamens and style united to form a column opposite the labellum. Top of the column sometimes protrudes towards labellum into a beak like process called rostellum.

Pollen grains coherent in each cell into 1,2 or 4 pairs of globose waxy or powdery masses called pollinia which may be free or attached by a sterile stalk known as candicle. Stocky gland may be present at the base of candicle which is called Corpusculum. The staminodes may be foliaceous (Diuris) or in the form of auricles (Orchis).

Gynoecium:

Tricarpellary, syncarpous, ovary inferior, unilocular, parietal placentation, stamen, stigma and style united together to form column or gynoecium. The portion of style in column is strong. Stigma lobes three of which only two lateral are fertile (all the three fertile in Cypripedium). Third is sterile and modified into rostellum.

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Fruit: Is a capsule.

Pollination: By insects.

Economic Importance

Aerides & Vanda are epiphytes with leafy stems. Roots of vanda are well known to the students for their peculiar anatomy. The special velamen thikening absorb moisture. Tubes of Eulophia epidendrae are used as vermifuge. Root stocks of Geodorum densiflora are used as insecticides. Roots of Vanda roxburghii is used for rheumatism and scorpion bite. Leaves of Calanthe veratriflora yield blue dye.

Ornamental plants of Papliopedalum are very costly. Dried pulpy fruits of Vanilla palfolia yield vanilla scent which is so extensively used in ice creams, chocolates and confectionary. Systemic Position:

Angiospermae

Monocotyledons

Corolliferae

Orchidales

Orchidaceae.

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