Aloes and Lilies of Ethiopia and Eritrea

84 ALOACEAE
Fig. 42. Aloe
trigonantha,
from south of
Bahir Dar, Gojam
floristic region.
Habitat and
distribution
Aloe rivae
Description
The species grows on dry stony ground near roads and
along field margins between 1900 and 2100 m in Gonder
and Gojam regions. It is so far not known anywhere
else. The main flowering period is from September to
January.
27. Aloe rivae Baker
The specific epithet ‘rivae’ is given in honour of the
Italian medical Doctor, Dome nico Riva, who made an
expedition to Sou thern Ethiopia in 1893 together with
Count Eugenio Ruspoli from whose collection the type
of the species was described in 1898. The type material
was collected at Gobbo Duaya, an area between Corroma
and Burji in Sidamo floristic region.
A. rivae is in a group of aloes (numbers 21–22 and
26–27) which often has secondary branching (up to
50 racemes or more) and which usually is stemless,
but some old plants develop thick, prostrate stems. A.
rivae is distinguished from the rest of the group by the
particularly bran ched inflorescence, and also by occurring
in a different geographical area. It is the only species in
the group known from the southern part of Ethiopia. The
other species only occurs in the central and northern
Ethiopia.
Rosettes usually stemless, sometimes with pro cum bent to ascending
stem, up to 60 cm long, solitary or in small groups. Leaves ca. 20,