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 1,000 genera and over 20,000 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 16 genera and 46 species with a single endemic
species that is also endangered (see North
American taxa).
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 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.
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