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Plant Highlight: Aloe sabaea
by Brian Kemble
Area of occurrence
There are quite a few species of Aloe native to the Arabian Peninsula, and most of these are stemless or short-stemmed rather than tall. An exception is Aloe sabaea, found in Yemen as well as in Saudi Arabia, and it has no apparent close relatives on the peninsula. The distribution of this species follows the mountain chain that runs parallel to the Red Sea, from southwestern Saudi Arabia in the north down through western Yemen, with an outlier population to the east in Yemen’s Hadhramaut region. It grows on dry rocky hillsides at altitudes ranging from 1,000 to 6,600 feet (300 to 2,000 m).
About the plant
Aloe sabaea is a single-headed species, with a slender stem that can reach a height of up to 10 feet (3 m). Its long tapering light green succulent leaves are 26 to 40 inches long (65 to 100 cm), with a width at base of 3.2 to 5.5 inches (8 to 14 cm). They are shallowly channeled rather than flat, and there is a narrow white to pinkish translucent border along most of their length, bearing small white teeth at irregular intervals. In some populations, the leaves arch out gracefully, while in other cases they are somewhat flexed near the base, so that they tend to droop downward alongside the stem. The leaves are shed when they dry, so that the stems are not clad in a skirt of dried leaves, as is the case with many tall aloes.
About the flowers
In its home range, the peak flowering for A. sabaea is in November and December, but plants in cultivation in California tend to be later than this. Our plants at the Ruth Bancroft Garden have typically begun flowering in late January to February, ending in March or April. The inflorescences are multi-branched and up to 40 inches tall (1 m), with each branch ending in a conical (or rounded-conical) raceme of coral-red or red-orange tubular flowers, yellowing at the mouth as they mature. The flower tips are slightly spreading to curled back, with the six stamens and the central pistil protruding from the mouth. The perianth length is up to a little over an inch (26 mm), with a diameter of .3 to .4 inch (8 to 10 mm). Younger plants may have only a few inflorescence branches, while large older plants may have dozens.
About the fruits and seeds
A pollinated flower develops into a glossy green oval seed capsule, with three slightly bulging sections and shallow grooves between them. The grooves indicate the three chambers within, holding stacks of seeds. When the capsule dries and turns brown, it splits open along the grooves, allowing the seeds to spill out. The capsule length is .8 to .95 inch (20 – 24 mm), with a width of ,4 to .47 inch (10 to 12 mm). The seeds are dark and 3-angled, with short gray papery wings surrounding the kernel. They are .16 to .2 inch long (4 to 5 mm).
Plants in cultivation
Aloe sabaea makes a striking garden plant in areas with a climate that is not too wet and with mild winters. In its home range, the average annual rainfall varies from 8 to 27 inches (150 to 700 mm). At the upper end of its altitude range, the species may get occasional freezing temperatures in winter, and in cultivation it can endure overnight lows down to the upper 20’s F (to about -3° C), but it cannot take extended periods below freezing. In the garden, it should be given a sunny position and excellent drainage.
Related species
Of all the Arabian species of Aloe, A. sabaea looks most similar to A. rivierei, somewhat resembling a taller and non-offsetting version of that species, but this is only a superficial resemblance. Its actual closest relatives seem to be two even taller-growing species from East Africa, A. ballyi and A. elata, and it shares with them not only a tall slender stem and a multi-branched inflorescence, but also poisonous sap that gives off a smell reminiscent of rat urine. In Kew Garden’s Plants of the World Online, the name Aloe sabaea is listed as a synonym under Aloidendron sabaeum, but this would leave it in a different genus than its closest relatives, which does not make sense if one is aiming for monophyletic genera.
