Astrophytum caput-medusae
Description of Astrophytum caput-medusae
Growth mostly single, rarely branched.
Beet root, fleshy, with cord-like lateral roots, and thus different from the previously known species of the genus Astrophytum. The seedling beet roots already develop in the age of half a year. It serves as a water reservoir.
Stem short-cylindrical, with slender, up to 19 cm long, 2-5 mm in diameter measuring warts at the head. They are cylindrical, slightly triangular and of slightly softer consistence at the base. One might suspect that the turgor controls the more vertical or horizontal appearance of the warts for more mimetic adaptation to the surrounding branches of the companion plants.
At the base of the warts there is a bush of hair that can be colored in nature intense brown. In culture, the bristly hairs are light cream colored to white. They structurally resemble to the bristles on the margins of the fertile part of the areoles.
The epidermis is blue-green to bright light grass green, joung warts intensively stained red depending of their position in the sunlight, warty. The surface feels rough. The warts are covered with white
flakes, scale-like trichomes. Their scale form arises through the parallel, fan-like compound of the hair. They adhere very firmly and can be rubbed off only with force. The thickness of individual hairs is about 8 microns and thus corresponds to the dimensions of Astrophytum myriostigma-hairs.
Areoles bisected, with 0-4 very fine spines on the wart tip, these 1-3 mm long, not seldom hooked backward, whitish with brown or dark tip, or brown to almost black. The fertile part of the areole has adaxial 18-46 mm (in culture 4 to 30 mm measured from middle of the areole) distance from the wart tip and is considerably larger, elliptical with white wool and brings light yellow
flowers with orange-throat, and some with a fine fragrancy. They have 53 (50-65) mm in diameter in 47 (55) mm in length. Very similar to Astrophytum but with a narrower pericarp, 19 mm long and coverd with dark-brown lanceolate scales and plenty of white wool. The flower tube is slender, up to 11 mm long, inside with pink tissue, as well as the pericarp. Outer perianth leaves inversely lanceolate, 19 mm long, yellow with a bright edge and toward the middle light green with a brownish center line to the tip and intense orange coloured base. Internal perianth leaves up to 24 mm long, intense yellow and orange base, fine serrated edges and an attached top. Numerous yellow stamens, 10-12 mm long. They are very closely advertised on the receptacle to the pistil-base and leave only a slit of 0.25 mm as nectar chamber. Up to a height of about 2 mm above the base of the flower, the primary filaments have short papillae, slightly less pronounced as with Astrophytum asterias. The yellow pencil is 18 mm long with 5 (3 to 10), straight stigma branches. The flower appears on the younger warts, when they dried up drops, it leaves a round stigma about 3 mm in diameter on the areole. It opens on the afternoon between 14.00 and 17.00 clock, closes on the first day slowly between 20.00 clock and midnight. On the second day it opens again as before, but closes completely about 21:00 clock, and will open in hot weather conditions on the third day no more. The flowering period extends from early April to late August (Lüthy, J., Dicht, R. (2007 p. 154).
Fruit slender ovoid, 20 mm to 50 mm long with 8 mm in diameter, fleshy green, with papery lanceolate, 1-2 mm long and 0.5 mm wide scales, bearing white wool in their axillae. It dries at maturity, and openss irregularly at the side. The fruit will open in about 5-6 weeks and unfold completely within 2-3 days. The flowers rest tilts to one side as in Austrastrophytum. The fruit wall is on opening juicy and green, pink at the base and just dries up later.
Seeds about 3 mm in size, hat formed, glossy black. In the ripe fruit they hang on swollen, white seminal appendages, which presumably serve the dispersal by ants. The elaiosome drys within a few days to brown.
Green seedlings, often purple flecked with sharp, large cotyledons as they do not occur elsewhere in the genus Astrophytum. Similarly, the hypocotyl is more slender and less succulent than any other species of the genus.
Mimesis branches of the accompanying bushes.
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A. caput-medusae