Thelocactus macdowellii

Thelocactus macdowellii, called the Chihuahuan snowball, is a species of cactus native to northeastern Mexico.^[2][3] It has gained the Royal Horticultural Society's Award of Garden Merit.^[4]

Thelocactus macdowellii
Conservation status
Near Threatened  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Cactaceae
Subfamily:	Cactoideae
Genus:	Thelocactus
Species:	T. macdowellii
Binomial name
Thelocactus macdowellii (Rebut ex Quehl) W.T.Marshall
Synonyms[2]
List Echinocactus macdowellii Orcutt Echinocactus macdowellii Rebut ex Quehl Echinomastus macdowellii (Orcutt) Britton & Rose Neolloydia macdowellii (Rebut ex Quehl) H.E.Moore Thelocactus conothelos var. macdowellii (W.T.Marshall) Glass & R.B.Foster

Description

Thelocactus macdowellii is a small, spherical cactus, typically 4 to 10 centimeters tall and 4 to 12 centimeters wide, with a yellowish apex covered in woolly hairs. It has 30 or more ribs, each with 5 to 7 millimeter high, conical, rhombic warts at the base. The areoles, initially woolly, bear 15 to 25 needle-shaped marginal spines, 1.5 to 2 centimeters long, and 3 to 4 central spines, each 3 to 5 centimeters long and straw yellow.

The flowers are funnel-shaped, 4 to 8 centimeters wide and up to 4 centimeters long, varying in color from rose red to magenta. The ovaries are smooth and have broad scales.

Distribution

Endemic to the Mexican states of Coahuila, Nuevo León, and the Chihuahuan Desert, Thelocactus macdowellii grows on scrubland and limestone hills in a very restricted area at an altitude of 1500 meters.^[5]

Taxonomy

First described as Echinocactus macdowellii in 1894 by Leopold Quehl, with the specific epithet honoring the Mexican gardener and plant collector José Alberto McDowell. The species was later placed in the genus Thelocactus by William Taylor Marshall in 1947^[6]