The Orchidaceae family, commonly known as orchids, is a diverse and captivating group of flowering plants. With over 28,000 species, orchids exhibit an astonishing array of forms, colors, and fragrances. From the iconic Phalaenopsis to the exotic Vanda, orchids can be found in a wide range of habitats, from tropical rainforests to temperate grasslands. Renowned for their intricate blooms and unique reproductive strategies, orchids have captured the imagination of botanists, artists, and collectors for centuries. This family offers endless opportunities for exploration and discovery, making it a fascinating subject for study and appreciation.
2. ORCHIDACEAE
The Orchid Family
Mostly epiphytic or
terrestrial perennial
herbs
15-20,000 species in
about 800 genera
Widespread distribution
Orchids are abundant in
the tropics, where they
are often epiphytic
Orchids are less common in cooler
temperate areas, where they have
a terrestrial habit
Spiranthes lucida
Liparis hawaiensis
3. Vegetative morphology
roots with velamen
pseudobulbs
Leaves 2-ranked, simple, entire, and coarsely
veined
Stems often basally thickened, forming a
pseudobulb (internode thickening) in
epiphytes
Roots of epiphytes have a multi-layered,
water-absorbing epidermis composed of dead
cells called velamen (harbor mycorrhizal fungi)
Mycorrhizal associates universal in roots
4. Floral morphology Ca 3 Co z
2 + 1 A 1 - 2 G ( 3 )
Perianth of 6 tepals in two
whorls of three or sometimes
with a distinct calyx & corolla
Flowers strikingly zygomorphic
Median petal larger and often
spurred or variously colored =
lip or labellum.
Flowers often resupinate
5. Calopogon, a common bog orchid of the northeastern US.
Non-resupinate flower of grass pink
resupinate
6. Floral morphology,
continued
Ca 3 Co z
2 + 1 A 1 - 2 G ( 3 )
Androecium of commonly 1 (primitively 2) stamen; usually pollen in 1 or 2
masses called pollinia.
Gynoecium of 3 united carpels; ovules numerous; ovary inferior
Stigma, style and the androecium are fused into a complex structure, the
column or gynandrium
Stigma 3-lobed, usually with a sterile central lobe called a rostellum
7.
8.
9. Fruit is a capsule with
abundant minute seeds
(several hundred per fruit)
10. Ophrys spp. - a genus well-known for
its bee-mimic flowers
Floral adaptation and pollination
15. Local members of the Orchidaceae
Spiranthes cernua
nodding ladies tresses
Isotria verticillata
Large whorled pogonia
Pogonia ophioglossoides
Rose pogonia
