Usually solitary Arabian highland aloe with glaucous gray, gray-green or gray-brown leaves and reddish pink (occasionally red or yellow) flowers. Stemless or nearly so. Leaves are erect and slightly rough in texture. Teeth are brown tipped, small, and closely and evenly distributed on the margins. Flowers appear in late summer and fall on inflorescences with up to 5 branches.

Described during Forsskål's 18th century explorations. Found in southwestern Saudi Arabia and Yemen at 4300-9800 feet. It is widely distributed, usually on rocky substrates. The rainfall over its range is about 8-47 inches. Yemeni plants tend to grow in drier locations; they are smaller, nearly always solitary, and grayer, with a higher likelihood of yellow flowers.

This species has absorbed the former A. dhalensis and A. audhalica, both described in 1965. No specimen survived the original exploration, and a subsequent collection over a hundred years later was incomplete, explaining the relative obscurity of the original A. vacillans at the time these other species were described.

This species resembles the Arabian castellorum, which has glossy, green leaves and tends to prefer more moisture. It is found with A. rubroviolacea. It is said to form natural hybrids with A. tomentosa (the plant formerly known as A. menachensis) and A. inermis.

This aloe may be very heat tolerant in cultivation.

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