Cactaceae
(Cactus Family)
Habit
-
stem succulents;
CAM metabolism; some
epiphytes
Leaves
-
alternate,
simple, and
entire,
estipulate; they are often minute and early
deciduous or absent;
axillary buds (called
areoles) flattened and usually
spine-producing
Inflorescence
- of solitary flowers produced by
axillary buds
Flowers
-
perfect;
hypanthium well developed in some species
Tepals
- numerous, spirally arranged; (the outer may be
sepaloid and the inner
petaloid)
Stamens
- numerous
Ovary
- distinctly
inferior (sunken into stem tissue that bears more
areoles) of 2-many
carpels with 1
locule and many
parietal placentae
Fruit
- berry
Diversity
- possibly 130 genera / 1700 species
Distribution
- all except 1 New World; occur from British Colombia to
Patagonia.
(African species is obviously related to Brazilian.)
Economics
- popular cultivated ornamentals; many in the wild are
on the verge of extinction
because unscrupulous collectors have dug them up--IT IS ILLEGAL IN ARIZONA!!!
Noxious weeds in some places where
introduced (Australia, Hawaii...)
Subfamilies
- Pereskioideae: leaves broad, flat;
glochids 0; seeds black, no
aril (the leaf cacti)
- Opuntioideae: leaves small,
terete;
glochids!!! (minute, almost invisible to the naked eye
spines at base of big ones); seeds with pale
aril or
winged
- Cactoideae: leaves 0 or very small,
glochids 0; seeds black, no
aril (the touchy-feelies with no
glochids)
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