A genus of sub-tropical species with slender tall, with 5 to n ribs. The spines are variable, the nocturnal, rather large, and borne near the top of the stems. The genus includes 19 species, many of which are popular with collectors. Harrisia eriophora. Cuba. A species well suited to cultivation. The plant has 8 to 9 ribs, the areoles bearing 6 to 9 spines. The flower has a greenish tube, with petals reddish outside and white inside.
Harrisia gracilis. Jamaica. The stems are slender, dark green, with 9 to 11 ribs; the areoles have 10 to 16 spines. The flowers are brownish outside and white inside. This plant requires warmth, and water must be withheld in cold weather.
Harrisia Martinii. Argentina. The stems are branched, green passing to greyish-green; radial spines are very short, numbering 5 to 7, with 1 central spine. The flowers are very beautiful and freely produced, the outer petals being pale green with reddish tips, the inner petals white.
Harrisia Bonplandii. Brazil, Argentina and Paraguay. The stems are bluish-green, passing to greyish, with 4 to 6 ribs. The areoles are greyish and bear 3 to 5 grey spines. This species has unusually beautiful flowers, with the outer petals brownish-green, the inner petals white.