Xerophyte

Habit

Solitary or rarely clustered up to 19 of eight.

Seeds

Big, up to 3 mm in length, cap-like, testa tuberculate , black or dark coffee coloured; hilum basal and very deep, micropyle, outside the hilum, but adjacent.

Description

Astrophytum caput-medusae f. nudumSN|3593]]SN|25784]] is the nude forms of Astrophytum caput-medusaeSN|25784]]SN|3593]] distinguished by having glossy green cylindrical tubercles almost completely lacking stigmas (squamiform peltate trichomes). There are no other clear distinguishing features, and they must all be regarded as the same species.

Roots

Primary root fusiform, fleshy; secondary roots fibrous. The root is of the same dimension or slightly smaller of the aerial part.

Tubercles

Cylindrical or occasionally triangular when young, of cartilaginous consistency, smooth, could appear similar in aspect to leaves, up to 190 mm in length and of 2 to 5 mm wide, some times the adaxial portion of the base of the tubercle is cuneate. Epidermis verrucose, glaucous-green, nude or with only few stigmas (squamiform peltate trichomes) of a greyish-white colour towards the tip of tubercles.

Flowers

Originates in the subterminal portion of the developing tubercles, not in the plant apex. The flowers are diurnal, yellow, with the base of the inner perianth segments orange coloured. Outer segments greenish yellow, The receptacular tube displays papyraceous, lanceolate scales, with terminal aristae and short white hairs in the axil; Lanceolate scales with white hairs in the axil are also presents in the pericarpel.

Spines

0 up to 4, generally persisting in old tubercles, of 1 to 3 mm in length, semi-erect, rigid, the base is whitish with a dark-coffee apex.

Stem

Very reduced, shortly cylindrical, lacking ribs, with papyraceous bristles covering the collar and the stem apex, the bristles probably originate from the basal rest of the tubercles, the colour of the bristles of tubercles is coffee whit reddish tones, the stem bristle of plants growing in habitat rarely exceed the ground level.

Fruits

Green and fleshy when young, covered with lanceolate scales with wool in the axil, dry when ripe with irregular longitudinal dehiscence.

Areoles

Dimorphic; the spiniferous one are terminals, circular or elliptical, with white wool; the floriferous one are located in the adaxial subterminal portion, separated from the spiniferous from 18 to 46 mm elliptical, with white wool, but noticeably larger than the spiniferous areoles.