The Liliidae
Family Overview - Orchidales

Orchidaceae  - the Orchid Family

Diversity:  perennial herbs, often epiphytic (tropics) and sometimes terrestrial (temperate) with floral adaptations similar to those of the Asclepidaceae of the Asteridae.  The largest monocot family and possibly the largest flowering plant family with over 800 genera and from over 22,000 to possibly 35,000 species including many ornamental domesticates and also the spice vanilla (Vanilla planifolia).

Distribution:  Worldwide and mostly pantropical with many temperate extensions. The Texas flora includes 21 genera and 57 species with a single endemic species that is also endangered (see North American taxa).

Floral structure:


gynoecium/androecium adnation - androecium reduced

Significant features:  Similar to families of the Liliales, i.e., perennial herbs with linear, 'monocot-like' leaves and various shoot features of the herbaceous perennial (bud, rhizome, corm, etc.).  Orchids are, however, often epiphytic with conspicuous adventitious roots.  Like the Ericaceae, this family has a strong association with fungi, mycorrhizal root associations and fungal assistance with seedling development. Zygomorphy is usually produced by the a single modified petal (the 'upper' petal - resupination) or labellum and, like the Asclepidaceae, the center of the flower is occuplied by a single structure (column or gynandrium) representing fusion of the gynoecium and androecium.  The anther contents are also massed in this family to produce pollen 'packages' or pollinia for vector transfer.  This diverse family produces the smallest angiosperms seeds, reduced to an undifferentiated embryo as a adaptation for wind dispersal to epiphytic safe sites.

Pogonia ophioglossoides (local bog orchid):

pogonia - flower
pogonia flower - close
plant
flower - with labellum, sepals, upper 2 petals

Encyclia cordigera:

encyclia - pollinia
calyx green
pollinia removed from the column

Vanilla planifolia (Overview from  Kohler's Medicinal Plants):

More information on the Orchidaceae


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