AREQUIPA. 
IOI 
understood. Arequipa is characterized by its slender, elongated, scarlet flower. The species 
are confined to the mountains of Peru and northern Chile. The generic name is that of 
the city in Peru near which the type species is found in great abundance. 
Key to Species. 
Hairs of flower-tube white; spines acicular.i. A. leucotricha 
Hairs of flower-tube brown; spines bristly. 2. A. myriacantha 
1. Arequipa leucotricha (Philippi). 
Echinocactus leucotrichus Philippi, Anal. Mus. Nac. Chile 1891': 27. 1891. 
Echinocactus clavatus Sohrens, Monatsschr. Kakteenk. 10: 27. 1900. 
Echinopsis hempeliana Giirke, Monatsschr. Kakteenk. 16: 94. 1906. 
Echinocactus rettigii Quehl, Monatsschr. Kakteenk. 29: 129. 1919. 
Plants simple or cespitose, sometimes branching, globular or sometimes elongated (4 to 6 dm. 
long) and then often prostrate, usually covered with spines but naked below when very old; ribs 
10 to 20, closely set, low; areoles close together; spines* 6 to 20-, slender; central spines much longer 
than the radials, 2 to 3 cm. long; flowers 5 to 6 cm. long, with a long slender tube, scarlet; scales on 
ovary and flower-tube small, with long white hairs in their axils; fruit globular, 2 cm. in diameter. 
Type locality: Naquira, Chile. 
Distribution: Vicinity of Arequipa, southern Peru to northern Chile. 
Dr. Rose found this species very common about Arequipa and for a long time he was 
unable to identify it. Its habit and dry fruit suggested some of the so-called species of 
Echinocactus but its slender red flower was not typical of that genus. It did not suggest 
the genus Echinopsis in any particular. A careful examination of the description of 
Echinopsis hempeliana Giirke and the cited illustration, however, points definitely to 
this Arequipa plant. The home of E. hempeliana was unknown to Giirke, but it is not 
unlikely that it was collected in southern Peru, perhaps at the time Opuntia hempeliana 
was found. 
Here belongs doubtless the Arequipa plant mentioned by Schumann under Echinopsis 
rhodacantha. 
After leaving Arequipa Dr. Rose went to Santiago, Chile, where he found in the her¬ 
barium of Dr. Philippi the type specimen of Echinocactus leucotrichus which has flowers 
almost identical with those of the Arequipa plant and we therefore adopt this specific name 
for the group. We have not seen specimens of Echinocactus clavatus but the illustration 
and description of the flowers point strongly to this species. 
Echinocactus hempelianus Schumann (Monatsschr. Kakteenk. 15: 178. 1905) is only 
a mentioned name. 
Illustrations: Bliihende Kakteen 2: pi. 85, as Echinopsis hempeliana; Schumann, 
Gesamtb. Kakteen Nachtr. f. 17; Monatsschr. Kakteenk. 10: 25, as Echinocactus clavatus. 
2. Arequipa myriacantha (Vaupel) 
Echinocactus myriacanthus Vaupel, Bot. Jahrb. Engler 50: Beibl. 111: 25. 1913. 
Simple, depressed-globose, 10 cm. in diameter, 8 cm. high; ribs 26, strongly tubercled, separated 
by an acute sinus; areoles closely set, broadly elliptic; spines slender, bristle-like, when young 
brown, in age dark gray, 25 or more, the longer ones 3 cm. long; flowers slender, tubular, 5 to 6 cm. 
long; axils of the scales on the flower-tube and ovary bearing long silky brown hairs. 
Type locality: Above Balsas in the provinces of Chachapoyas, Department of Ama¬ 
zonas, Peru, altitude 2,200 meters. 
Distribution: Northeastern Peru. 
This species is related to Arequipa leucotricha, but it has very different armament. 
Through the kindness of F. Vaupel we have been able to examine a fragment of the 
type of this species which was collected by A. Weberbauer (No. 4272) and is now pre¬ 
served in the herbarium of the Botanical Garden at Berlin. 
*In seedlings and even in small 5 to 6 year-old plants the spines are pilose. 
