Xerophyte

Seeds

Globular, 2 mm in diameter.

Description

Discocactus hartmanniiSN|12017]]SN|33218]] is a low growing cactus species with simple stems, that are broader than high with rounded ribs cut by deep wrinkles into flat humps. At maturity the plant is crowned by a brown bristly cephalium. The flower opens at night and smells like lily of the valley. It is one of the geographical or morphological forms of Discocactus heptacanthusSN|33218]]SN|12017]] which is one of the most widespread and morphologically variable taxon.

Taxonomy

The names Discocactus hartmanniiSN|12017]]SN|33218]] is not accepted by many botanists that treat it as synonym of Discocactus heptacanthusSN|33218]]SN|12017]] subs. magnimammus, but it has perianth-segments more acute (not rounded like in subs. magnimammus), and it still has a value for a collector because they identify plants with particular characters.

Cephalium

Composed of long wool and many erect bristles.

Flowers

Up to 10 cm long, white. Flower-tube funnelform, bearing a few spreading scales. Outer perianth-segments green. Inner perianth-segments lanceolate to nearly oblong, acute, white.

Spines

Yellow, up to 2 cm long and up to 1,5(-2) mm thick, subulate, often slightly flattened. Radial spines 6 to 12, curved backward and appressed. Central spines solitary, up to 1 cm long.

Ribs

12 to 22, broad at base, obtuse, bumpy, completely divided transversely into large tubercles.

Stem

Solitary, flattened globose, green, shining up to 6 cm. tall and 15 cm wide.

Fruits

Yellow, thin-skinned..