Thelocactus bicolor var. flavidispinus

Backeberg

Beitr. Sukkulentenk. Sukkulentenpflege 1941: 6. 1941.

Endemic
Treatment appears in FNA Volume 4. Treatment on page 218.

Plants unbranched (very rarely branched), deep-seated in substrate. Stems flat-topped when young, ± spheric (rarely short cylindric when old), 3–9 (–13) × 4–6 (–7) cm, surface hidden by spines; ribs poorly defined, ca. 13, tubercles confluent only at extreme bases (youngest sexually mature plants strictly tuberculate), 8–15 mm wide; areoles spaced 6–15 mm apart along ribs. Spines yellow (very rarely some individuals red); radial spines 12–20 per areole, longest spines 9–18 (–24) mm; adaxial (bladelike) spines 18–35 (–40) × 0.5–1.5 mm; central spines (0–) 1 (–4), longest spines terete, (9–) 13–18 (–24) × 0.4–0.5 mm. 2n = 22.


Phenology: Flowering Mar–Sep.
Habitat: Caballos novaculite outcrops in semidesert grasslands
Elevation: 1200-1300 m

Discussion

Thelocactus bicolor var. flavidispinus is the most widespread of the several taxa of cacti endemic to novaculite, a highly fractured, quartzlike rock. Unusually tall and/or red-spined individuals within populations of var. flavidispinus have been the basis for mistaken reports of var. bicolor in the region of novaculite, where only var. flavidispinus occurs. The reports of var. flavidispinus in south Texas (Starr County; L. D. Benson 1982) are based on misidentified T. bicolor var. bicolor.

Selected References

None.

Lower Taxa

None.
3.5 cm35 mm <br />0.035 m <br /> (4 cm40 mm <br />0.04 m <br />) +
18mm +  and 35mm +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
cushionlike +
apart +  and spaced +
circular to linear +
2 cm20 mm <br />0.02 m <br /> (5.2 cm52 mm <br />0.052 m <br />) +
deciduous +  and persistent +
hourglass--shaped +
0.6 cm6 mm <br />0.006 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Allan D. Zimmerman +  and Bruce D. Parfitt +
Backeberg +
hardened +
Echinocactus bicolor +
triangular +
4.2 cm42 mm <br />0.042 m <br /> (5.8 cm58 mm <br />0.058 m <br />) +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
curved +  and straight +
13mm +  and 42mm +
angled +, flattened +  and terete +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
proliferating +
flattened +  and cylindric +
not mucilaginous +
notched +
1200-1300 m +
not separating +
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 />) +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
1.2 cm12 mm <br />0.012 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
green;brownish purple +
persistent +, long +  and deciduous +
7mm;18mm +
spheric +  and short cylindric +
not juicy +
0.6 cm6 mm <br />0.006 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
conspicuous +
Caballos novaculite outcrops in semidesert grasslands +
2.8 cm28 mm <br />0.028 m <br /> (5 cm50 mm <br />0.05 m <br />) +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 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 +
1.8 cm18 mm <br />0.018 m <br /> (2.4 cm24 mm <br />0.024 m <br />) +
1.8 cm18 mm <br />0.018 m <br /> (2.4 cm24 mm <br />0.024 m <br />) +
13mm +  and 18mm +
0.9 cm9 mm <br />0.009 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
fringed +  and denticulate +
deciduous +  and persistent +
Flowering Mar–Sep. +
not mucilaginous +
older +  and young +
ridgelike +  and nipple--shaped +
Beitr. Sukkulentenk. Sukkulentenpflege +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
tuberculate +
5 +  and 21 +
triangular +
arillate +  and strophiolate +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
papillate +
cylindric;pyriform +
constricted +
0.1 cm1 mm <br />0.001 m <br /> (0.175 cm1.75 mm <br />0.00175 m <br />) +
3.5 cm35 mm <br />0.035 m <br /> (4.5 cm45 mm <br />0.045 m <br />) +
7.5 cm75 mm <br />0.075 m <br /> (10 cm100 mm <br />0.1 m <br />) +
straight +
deciduous +  and persistent +
9mm +  and 35mm +
12 (?) +  and 20 (?) +
ribbonlike +, bladelike +  and flattened +
1.6 cm16 mm <br />0.016 m <br /> (7.5 cm75 mm <br />0.075 m <br />) +
hard +  and rigid +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
0-4 times wider than thick +
decurrent +
8 cm80 mm <br />0.08 m <br /> (10 cm100 mm <br />0.1 m <br />) +
6.5 cm65 mm <br />0.065 m <br /> (10 cm100 mm <br />0.1 m <br />) +
4 cm40 mm <br />0.04 m <br /> (8 cm80 mm <br />0.08 m <br />) +
4 cm40 mm <br />0.04 m <br /> (6.5 cm65 mm <br />0.065 m <br />) +
unsegmented +
6 cm60 mm <br />0.06 m <br /> (7 cm70 mm <br />0.07 m <br />) +
3cm;9cm +
spheric +  and flat-topped +
succulent +
4cm;6cm +
reddish +  and red-orange or pale reddish-brown or yellowish +
tuberculate +
adventitious +
tuberlike +
epipetric +  and epiphytic +
Thelocactus bicolor var. flavidispinus +
Thelocactus bicolor +
variety +
dull +  and glossy +
compressed +, pyramidal +, conic +  and rounded +
8mm +  and 15mm +
epiphytic;epiphytic;epiphytic +
barrel-shaped +  and spheric +