Pilosocereus robinii

(Lemaire) Byles & G. D. Rowley

Cact. Succ. J. Gr. Brit. 19: 67. 1957.

Common names: Key tree cactus
IllustratedConservation concern
Basionym: Pilocereus robinii Lemaire Ill. Hort. 9: 74. 1864 (as robini)
Synonyms: Cephalocereus deeringii Small Cephalocereus keyensis Britton & Rose Cereus robinii (Lemaire) L. D. Benson Cereus robinii var. deeringii (Small) L. D. Benson Cereus robinii var. keyensis (Britton & Rose) L. D. Bens on ex R. W. Long & Lakela Pilosocereus deeringii Pilosocereus keyensis Pilosocereus robinii var. deeringii (Small) Kartesz & Gandhi
Treatment appears in FNA Volume 4. Treatment on page 180. Mentioned on page 181.

Plants erect, normally with few–many, closely parallel branches forming a narrow crown. Stems light to deep green, or blue-green especially when young; ribs 9–13; areoles copiously hairy; hairs deciduous to persistent, long or short. Spines 9–31 per areole; longest spines 10 mm. Flowers campanulate, 5–6 cm; outer tepals light green with brownish midstripes, ovate to obovate, apex acute to obtuse; inner tepals white; outermost ovate to elliptic, innermost oblanceolate to broadly linear. Fruits sometimes with 1–2 scales. Seeds 2 mm.


Phenology: Flowering (Mar-)Aug–Sep; fruiting year-round.
Habitat: Upland tropical hardwood hammocks, "cactus hammocks" (low elevation thorn scrub), sandy soils, nearly bare coral rock
Elevation: 0-10 m

Discussion

Of conservation concern.

In the flora, Pilosocereus robinii has been known historically from Key West to Key Largo, Florida, but is now restricted to Upper and Lower Matecumbe Keys, Long Key, and Big Pine Key. Pilosocereus keyensis and P. deeringii were originally described (as Cephalocereus species) from Key West and Lower Matecumbe Key, respectively, where they supposedly were endemic. Recent authors (D. F. Austin 1984; A. N. Lima and R. N. Adams 1996; R. P. Wunderlin and B. F. Hansen, www.plantatlas.usf.edu) have considered them to be within the range of variation of P. robinii. Although E. F. Anderson (2001) treated all of those named variants and others as merely insular forms of P. polygonus (Lamarck) Byles & G. D. Rowley, such treatment remains to be supported by a populational study throughout the West Indian range of the taxa.

In 1992, a clone identified as Pilosocereus bahamensis (Britton & Rose) Byles & G. D. Rowley was discovered in a rock hammock surrounded by mangrove swamp on Key Largo, Florida. E. F. Anderson (2001) also included that species as a synonym of P. polygonus.

When main stems fall to the ground, for whatever reason, the lateral branches develop into plants with the ‘unbranched’ pattern that was the basis for Small’s concept of Cephalocereus deeringii (D. F. Austin 1984).

According to L. D. Benson (1982), when the flowers initially open in the afternoon they may have an odor of onion or garlic.

Pilosocereus robinii is in the Center for Plant Conservation’s National Collection of Endangered Plants.

Selected References

None.

Lower Taxa

None.
... more about "Pilosocereus robinii"
Acute (?) +  and Obtuse (?) +
cushionlike +
confluent +, adjacent +  and spaced +
circular +  and elliptic +
deciduous +  and persistent +
hourglass--shaped +
Bruce D. Parfitt +  and Arthur C. Gibson +
(Lemaire) Byles & G. D. Rowley +
hardened +
Pilocereus robinii +
triangular +
few +  and many +
not distinguishable +
proliferating +
flattened +  and cylindric +
Key tree cactus +
mucilaginous +
Fla. +, Mexico +  and West Indies +
0-10 m +
not separating +
6 cm60 mm <br />0.06 m <br /> (9 cm90 mm <br />0.09 m <br />) +
5 cm50 mm <br />0.05 m <br /> (7 cm70 mm <br />0.07 m <br />) +
crepuscular +  and nocturnal +
5 cm50 mm <br />0.05 m <br /> (6 cm60 mm <br />0.06 m <br />) +
lateral +  and subterminal +
5 cm50 mm <br />0.05 m <br /> (6 cm60 mm <br />0.06 m <br />) +
15 cm150 mm <br />0.15 m <br /> (30 cm300 mm <br />0.3 m <br />) +
curved +  and straight +
0.2 cm2 mm <br />0.002 m <br /> (15 cm150 mm <br />0.15 m <br />) +
persistent +, long +  and deciduous +
clavate +, spheric +  and depressed-spheric +
dry +, fleshy +  and juicy +
Upland tropical hardwood hammocks, "cactus hammocks" (low elevation thorn scrub), sandy soils, nearly bare coral rock +
0.8 cm8 mm <br />0.008 m <br /> (5 cm50 mm <br />0.05 m <br />) +
tawny +  and white +
deciduous +  and persistent +
longest +
0 cm0 mm <br />0 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0.9 cm9 mm <br />0.009 m <br /> (2.6 cm26 mm <br />0.026 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 +
10 cm100 mm <br />0.1 m <br /> (?) +
denticulate +  and entire +
deciduous +  and persistent +
Flowering (Mar-)Aug–Sep +  and fruiting year-round. +
mucilaginous +
ridgelike +  and nipple--shaped +
Cact. Succ. J. Gr. Brit. +
rounded +
purple +  and red +
indehiscent +
2 cm20 mm <br />0.02 m <br /> (4.5 cm45 mm <br />0.045 m <br />) +
1 +  and 2 +
depressed-spheric +
30mm +  and 50mm +
arillate +  and strophiolate +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
snail--shaped +
Illustrated +  and Conservation concern +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
purple +, red +, gray +  and yellow +
straight +
indehiscent +
deciduous +  and persistent +
20mm +  and 45mm +
9 (?) +  and 31 (?) +
depressed-spheric +, terete +  and acicular +
3 cm30 mm <br />0.03 m <br /> (5 cm50 mm <br />0.05 m <br />) +
decurrent +
unsegmented +
2.8 cm28 mm <br />0.028 m <br /> (5 cm50 mm <br />0.05 m <br />) +
light +  and deep green or blue-green +
columnar +
succulent +
5cm;8cm +
tuberculate +
Cephalocereus deeringii +, Cephalocereus keyensis +, Cereus robinii +, Cereus robinii var. deeringii +, Cereus robinii var. keyensis +, Pilosocereus deeringii +, Pilosocereus keyensis +  and Pilosocereus robinii var. deeringii +
adventitious +
tuberlike +
epipetric +  and epiphytic +
Pilosocereus robinii +
Pilosocereus +
species +
dull +  and glossy +
epiphytic;epiphytic;epiphytic +
barrel-shaped +  and spheric +