Xerophyte

Leaves

Only on young joints, spreading, dark red, about 2 mm long.

Description

Opuntia stenopetalaSN|33808]]SN|33808]] is a low bushy plant, often forming thickets or mats, the main branches creeping and resting on the edges of the joints. Although in its habit this Opuntia is much like many others, its flowers are unique, the petals being very narrow and erect; it is a very beautiful plant, and at flowering timeis covered with numerous, small, beautiful flowers. Moreover Opuntia stenopetalaSN|33808]]SN|33808]] is a functionally dioecious (unisexual) species. Developmentally, both female and male flowers start out as hermaphrodites, with organ stalling occurring at subsequent stages of their formation. In male flowers, growth and morphogenesis of the gynoecium cease, resulting in the formation of a short style lacking stigmatic tissue and poor ovule development at maturity; while development of the androecium goes on unhindered and large amounts of viable pollen are produced. Conversely, anther development in the female flowers is aborted and no pollen grains are produced. O. stenopetala is one of the most valuable ornamental opuntias.

Cultivation

Small, smooth, 3 mm in diameter, with broad, rounded margins.

Stem Segments

Joints obovate to orbicular, 10 to 20 cm long, greyish green, but often more or less purplish, very spiny.

Flowers

Unisexual, small, including the ovary only 3 cm long; petals orange-red, very narrow, 10 to 12 mm long, with long acuminate tips. Ovary leafy, the upper leaves similar to the sepals. Female flowers with style very thick in the middle bearing 8 or 9 yellow stigma-lobes. Male flowers with an abortive, claviform style, dull pink and yellowish above with the lobules of stigma atrophied and ending in a sharp, rigid tip. Filaments short.

Chromosome Number

n = 11.

Spines

Usually reddish brown to black, but sometimes becoming pale, usually 2 to 4, thelongest ones 5 cm long, the larger ones somewhat flattened. Glochids very abundant on young joints, brown.

Fruits

Globular, 3 cm in diameter, acid, with or without spines.

Areoles

Often remote, 1 to 3 cm apart, the lower ones often without spines, bearing white wool when young.