Cactaceae

Plant Sex: Flowers bisexual

Flowers: Actinomorphic and zygomorphic. Sepals grade into petals. A floral cup (HYPANTHIUM) is usually present. Gynoecium with one locule, many parietal ovules.

Inflorescence: Flowers solitary and sessile

Fruits: Berries

Habit: Fleshy (succulent) perennials forming phylloclades. Some tree-like and some epiphytic (e.g. Rhipsalis)

Leaves: Simple, alternate (e.g. Pereskia) but usually early deciduous or reduced to spines. In Opuntia, spines raised upon an AREOLE with GLOCHIDS at base.

Examples:
Opuntia (prickly pear and cholla)

O. fragilis. Plant in flower. This is a native Illinois cactus photographed at the Savanna Army Depot in Carroll County.
O. stricta flowers in L.S.
Opuntia sp. from Mexico with fruits.
O. leptocaulis and O. imbricata, two cholla cactus species from Texas.
Opuntia has been introduced to many areas of the Old World where it has become a naturalized weed, such as this plant in South Africa.

Carnegia gigantea (saguaro)

Habit of the cactus Saguaro National Monument east of Tucson Arizona
Flowers
Fruits

Mammillaria (pincushion cactus)

Flowering plant from Arizona.
Another species from Mexico.

Ferocactus (compass barrel cactus)

Habit of cactus in flower.
Close-up of spines
Flower L.S.
F. wislizeni, the fishhook cactus. Habit and close-up of apex with flowers.

Myrtillocactus

A large columnar species from Mexico.

Lophophora williamsii (peyote)

Some types of epiphytic cacti:

Epiphyllum (orchid cactus)

E. oxypetalum. Cultivated plant in flower.
E. oxypetalum. Flower, face view.

Hatiora gaertneri (Easter cactus)

Habit of a cultivated plant
flowers

Schlumbergera (Christmas, Thanksgiving cactus)

Habit of potted S. bridgesii in flower
Flowering shoot
Flowers
Flower L.S.
Flower in male phase and another in female phase

SIUC / College of Science / Elements of Plant Systematics
URL: http://www.plantbiology.siu.edu/PLB304/Lecture14Caryop/Cactaceae.html
Last updated: 28-Feb-08 / dln