Orchidaceae
(Orchid Family)
Habit
- Herbs, many
epiphytic, some vines and
saprophytes; roots of epiphytes covered with
velamen --
dead
epidermal cell layer 2-18 layers that are spongy,
water absorbtive; growth habits --
sympodial,
monopodial
Leaves
-
alternate or all
basal,
simple,
sheathing
Inflorescence
- mostly a
spike or flowers solitary
Flowers
- perfect (in ours),
resupinate, extremely
zygomorphic
Sepals
- 3, often petaloid
Petals
- 3, 2 similar, the third often very different and called a
lip or
labellum and
variously appendaged,
spurred or forming a slipper
(saccate)
Stamens
- 1 (2-3)
adnate to stigma and style; pollen grains shed in wayx masses
(called
pollinia connected by sticky gland called a
viscidium or subtended by a flap called
rostellum--
both are derived from middle stigma lobe).
Gynoecium
- of 3
carpels;
ovary inferior with 1
locule and usually 3
parietal placentae (ovules minute)
Style
- massive and with
adnate stamens forming
column
Fruit
- a capsule with thousands to millions of dust-like seeds
Diversity
- 700 genera / >25,000 spp.
Distribution
- extremely cosmopolitan--grow very near the limits of
vegetation (latitudinally and altitudinally), from northern
Sweden to
Tierra del Fuego;
Economics
- Vanilla (trop. America); fruits and seeds used by Aztecs to flavor cocoa;
many genera are ornamentals causing
insanity
in some humans…
Notes
-
Images
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