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Plant Highlight: Kalanchoe tomentosa
By Brian Kemble
Taxonomic placement and area of occurrence
Kalanchoe is a fairly large genus in the Crassulaceae, or Stonecrop Family, with 138 species listed in the Illustrated Handbook of Succulent Plants: Crassulaceae, published in 2003. Of these, 63 species are from Madagascar, with an additional species found in the adjacent Comoro Islands. Most of the rest occur in Africa, with a few also occurring in the Arabian Peninsula, Asia, and the island of Socotra. Among those from Madagascar are some with considerable horticultural appeal, including Kalanchoe tomentosa, sometimes called the panda plant on account of its furry leaves. It comes from Madagascar’s central highlands, to the south of Antananarivo.
About the plant
Kalanchoe tomentosa is a perennial that offsets at the base to form a cluster of erect slender stems (woody at the base), typically around 4 to 8 inches tall (10 – 20 cm) when not in flower, though robust specimens may be taller than this. Though always densely hairy, the thick leaves are variable in shape and size. They may be short and more or less oval, or more elongated and either parallel-sided or widened at the middle. The upper surface is concave, either shallowly or conspicuously like a dugout canoe, while the lower surface is convex. The margins are rounded and without teeth or in the lower part, becoming shallowly crenellated toward the tip and bearing small blunt teeth. Although the teeth are small, they are made conspicuous by a darkening of the hairs around them. The lower leaves in a rosette may lack the teeth altogether. The hairs covering the leaf are variable in length from one population to another. They are usually white or whitish, but they may be gold-tinged or brown-tinged, while the hairs around the teeth are dark brown to reddish-brown. The leaf length varies from .8 inch to 3.15 inches (2 to 8 cm), with the base narrowing to meet the stem, but without a petiole (leafstalk).
About the flowers and fruits
When a stem flowers, the growing tip elongates into a tall slender flower stalk, reaching a height of up to 40 inches (1 m). Like the plant from which it arises, the stalk is covered with hairs, and at intervals along it are bracts that look like smaller versions of the leaves, decreasing in size as they go up. The upper part of the inflorescence has short floral branches holding clusters of tubular flowers. The flowers are clasped at their bases by four triangular hairy sepals up to .2 inch long (5 mm), ranging in color from yellow to brown. The outsides of the flowers are hairy as well, and the base of the tube is yellow or greenish-yellow, darkening upward to yellow-brown or dark brown. At the tip, the tube separates into four lobes, these usually flaring outward to some extent. The inside of the flower is dark purple, often with a whitened rim, and with streaks of yellow or greenish yellow farther down the tube, giving way to all greenish-yellow in the cupped lower part. The flowers are variable in length, but are on average about a half inch (12.5 mm). Within the flower, the 8 short stamens emerge from the sides of the floral tube about halfway down. At the center of the flower are the four carpels where the seeds are produced, and these measure about a quarter-inch from their bases to the stigmas at their summits (a little over 6 mm). As is usual in the Crassulaceae, the carpels hold many tiny seeds that are wind-dispersed after the ripe carpel splits open.
Plants in cultivation
Kalanchoe tomentosa is frequently grown as a potted plant, but it can be planted out where winters are mild. It can endure only brief dips below freezing, so it is not suitable outdoors where cold spells in winter exceed this. At the Ruth Bancroft Garden, we grow it in a bed that gets covered in winter to protect it from the cold. It grows on rocks in nature, so good drainage is important, and it wants plenty of sunlight to keep it compact, though it should be protected from the full brunt of the afternoon sun in hot places.
