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Plant Highlight: Aloe vacillans

November 2007

At the Ruth Bancroft Garden, we grow a number of Aloe species which come from the Arabian Peninsula, and one of these is the fall-blooming Aloe vacillans, which occurs mostly in Yemen, but also across the border in southwestern Saudi Arabia.

Both yellow-flowered and red-flowered forms of the species can be found.  Yellow blooms are predominant in the rugged mountain range that runs parallel to the Red Sea coast in the western part of Yemen, but over the border in southern Saudi Arabia the flowers are often red.  Small forms of the species with red flowers are also found to the east on the Audhali plateau, and these were formerly called Aloe audhalica.  A southern form, usually with yellow flowers but smaller than the typical form, was given the name Aloe dhalensis, but it too is now considered a synonym of A. vacillans.

The leaves of Aloe vacillans are a glaucous-green color, with a grayish waxy bloom that becomes tinged with violet in bright sun.  Under drier conditions the leaves are held more erectly and bunched together, while under lusher conditions they are more spreading.  They are wide at the base and taper to a point, with small brown teeth along the edges.  Larger forms of the species may be 2 or 3 feet tall, not counting the bloom stalk, while shorter ones may be only a foot tall.  All are attractive plants, and they may be single-headed, though they usually form a small clump by producing offsets.

In gardens in our area, these plants normally begin flowering in October and finish in December.  Taller forms may have several-branched flower stalks up to 5 or 6 feet tall, while shorter ones are only 2 or 3 feet.  They make fine garden plants if given excellent drainage and a sunny position, and they can endure temperatures at least into the upper twenties Fahrenheit.