Astrophytum

Lemaire

Cact. Gen. Sp. Nov., 3. 1839.

Etymology: Greek asteros, star, in reference to the star-shaped stem cross section of the type species, and phyton, plant
Treatment appears in FNA Volume 4. Treatment on page 191. Mentioned on page 96.

Plants stem succulents, unbranched [to several branched from base], mostly low and deep-seated in substrate [taller in Mexican species]. Roots diffuse. Stem unsegmented, dark green or gray-green, hemispheric or depressed-spheric [to spheric or short cylindric], (2.5–) 6–15 (–60) [–100] × 6–10 (–20) cm, speckled [or entirely hidden] by numerous tufts of dense, whitish, multicellular hairs less than 0.5 mm; ribs [4–] 8–10, crests uninterrupted, straight [to sinuous and/or helically curving around stem], broad and nearly flat or rounded [sharp or keeled]; areoles distinct, [2–] 6–9 [–20] mm apart along ribs, circular; areolar glands absent; cortex and pith hard, not mucilaginous. Spines absent [1–25 per areole in some Mexican species]. Flowers diurnal, near stem apex, at adaxial edge of areoles, funnelform, 4.5–5.4 [–8] × 3.8–5.2 [–6] cm; inner tepals yellow, proximally red [all yellow], 25 × 6–10 [–12] mm, margins entire; ovary sparsely to densely scaly, axils spineless long hairy with arachnoid trichomes, distal scales spine-tipped; stigma lobes [8–] 10–12, yellow [pale yellowish], 4 mm. Fruits indehiscent or splitting irregularly, green or pinkish to red, ovoid to spheric, 15–20 × 12 mm, initially fleshy, drying immediately after ripening, sparsely to densely scaly with spine-tipped scales; axils of scales long woolly, spineless; floral remnant persistent. Seeds dark-brown to blackish, appearing hollow or bowl-shaped from strongly expanded, inrolled rim around sunken hilum, 2–3 mm in greatest dimension, nearly smooth; testa cells very slightly convex. x = 11.

Distribution

sw United States, Mexico

Discussion

Species 4–5 (1 in the flora).

Astrophytum is most often recognized as a distinct genus. Chloroplast DNA evidence (C. A. Butterworth et al. 2002), however, confirms that it is among the closest relatives of Echinocactus. Unlike Echinocactus, the stem surfaces of Astrophytum species are speckled by numerous tiny white tufts of minute, matted hairs in addition to the regularly spaced woolly areoles.

Selected References

None.

... more about "Astrophytum"
cushionlike +
0.9 cm9 mm <br />0.009 m <br /> (2 cm20 mm <br />0.02 m <br />) +
deciduous +  and persistent +
hourglass--shaped +
0.6 cm6 mm <br />0.006 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
Allan D. Zimmerman +  and Bruce D. Parfitt +
Lemaire +
spineless +
hardened +
triangular +
proliferating +
flattened +  and cylindric +
not mucilaginous +
uninterrupted +
straight +
rounded +  and flat +
sw United States +  and Mexico +
not separating +
Greek asteros, star, in reference to the star-shaped stem cross section of the type species, and phyton, plant +
5.4 cm54 mm <br />0.054 m <br /> (8 cm80 mm <br />0.08 m <br />) +
5.2 cm52 mm <br />0.052 m <br /> (6 cm60 mm <br />0.06 m <br />) +
4.5 cm45 mm <br />0.045 m <br /> (5.4 cm54 mm <br />0.054 m <br />) +
15 cm150 mm <br />0.15 m <br /> (30 cm300 mm <br />0.3 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (15 cm150 mm <br />0.15 m <br />) +
3.8cm;5.2cm +
pinkish;red +
splitting +  and indehiscent +
persistent +, long +  and deciduous +
15mm;20mm +
ovoid +  and spheric +
12 cm120 mm <br />0.12 m <br /> (?) +
multicellular +
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
25 cm250 mm <br />0.25 m <br /> (?) +
deciduous +  and persistent +
rudimentary +
flat +  and terete +
nearly +  and microscopic +
0 cm0 mm <br />0 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
tuberculate +
fluted;spheric;depressed-spheric or club-shaped +
deciduous +  and persistent +
not mucilaginous +
ridgelike +  and nipple--shaped +
Cact. Gen. Sp. Nov., +
expanded +
triangular +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
bowl--shaped +
deciduous +  and persistent +
0 (?) +  and 90 (?) +
annulate-ridged +, hairlike +, daggerlike +, subulate +  and acicular +
hard +  and rigid +
decurrent +
unsegmented +
10 cm100 mm <br />0.1 m <br /> (20 cm200 mm <br />0.2 m <br />) +
speckled +, gray-green +  and dark green +
6cm;15cm +
depressed-spheric +  and hemispheric +
succulent +
6cm;10cm +
tuberculate +
adventitious +
tuberlike +
epipetric +  and epiphytic +
Astrophytum +
Cactaceae subfam. Cactoideae +
dull +  and glossy +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
unbranched +  and branched +
plant +, climbing +, scrambling +, geophytic +, shrub +  and tree +
epiphytic;epiphytic;epiphytic +
hanging +  and erect to prostrate +
barrel-shaped +  and spheric +