Digitostigma caput-medusae
Cact. Suc. Mex. 47(4): 81 (76-86; figs. 1-14). 2002 [Dec 2002] replaced by Astrophytum caput-medusae D. R. Hunt (2003)
Family
Cactaceae
Genus
Species
Digitostigma caput-medusae
Author
Velazco & Nevárez
Chinese genus
-
Chinese name
-
Primary
Accepted
DescriptionEdit description
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
Solitary or rarely clustered up to 19 of eight.
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, covered by stigmas (squamiform peltate trichomes) of a greyish-white colour, covering almost the totality of the epidermis towards the base of the the tubercle.
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.