fbpx

Plant Highlights

Plant Highlights By Date Plant Highlights Alphabetically

Plant Highlight: Tylecodon wallichii

July 2024

By Brian Kemble


 

Family placement and area of occurrence

Tylecodon is a genus in the Crassulaceae, or Stonecrop Family, with 46 species recognized in the 2004 book Cotyledon and Tylecodon, by Ernst van Jaarsveld and Daryl Koutnik. At one time, the species now in Tylecodon were included in Cotyledon, but in 1978 the genus Tylecodon was described by Toelken, separating out the species with an alternate leaf arrangement and a summer-deciduous growing habit. Note that Tylecodon is an anagram of Cotyledon.

The species of Tylecodon are heavily concentrated in the winter-rainfall region of western South Africa and southern Namibia, though a few have large distributions that extend outside this area. While some species are geophytes, dying back to an undeground tuber during the dormant season, others have swollen basal caudexes or conspicuous succulent stems. One of the latter is Tylecodon wallichii, occuring over an extensive area in the western part of South Africa and across the border into the southwestern corner of Namibia. While it occurs in the winter-rainfall area, it tends to be found in relatively dry places, where the annual precipitation is less than 15 inches (380 mm).

About the plant

With its knobbly stems attaining a height of up to 20 inches (50 cm), Tylecodon wallichii is on the large side for the plants in its genus. Its smooth gray-green leaves emerge in the autumn, and they are more or less cylindrical, but with  a shallow groove running down the upper side and tapering to a pointed tip. Their length ranges from 1.6 to 6 inches long (40 to 150 mm), with a width of .08 to .24 inch (2 to 6 mm). At the base of each leaf is a more or less conical hardened woody protuberance called a phyllopodium (plural – phyllopodia), which means “leaf foot”. The leaves remain on the plant through the winter and spring months, but then begin withering at the tips as the plant comes into flower in esarly summer. They soon dry out completely and are shed, leaving the knobbly phyllopodia as a protective armor covering the softer interior of the stem. Plants may branch at the base to form a cluster of stems, but they also branch higher up to form a small shrub. The stem diameter is up to 1.2 inches (3 cm). During the winter growing season, the plant’s appearance is dominated by the tufts of cylindrical leaves atop each stem, but during the summer dormancy period the projecting phyllopodia are its most conspicuous feature.

About the flowers

In its home range in southern Africa, Tylecodon wallichii begins sending up its branching inflorescences in November and December, a little before the Summer Solstice, and with our opposite seasons in the Northern Hemisphere, this occurs at the Ruth Bancroft Garden in June. The height of the inflorescence is quite variable, and it may be as much as 28 inches (70 cm). Usually, however, it is less than this, topping out at something close to18 inches or less (45 cm). The peduncle (the stalk of the inflorescence), its branches, and the outsides of the flowers all have a sparse covering of short bristly and sticky hairs, though these are lacking in the subspecies ecklonianus. There are up to about 8 floral branches, and these angle upward. Each branch holds a modest number of short-tubular flowers with curled-back tips. At the bud stage, the flowers are a fuzzy pale green, clasped at the base by the 5 triangular sepals. When they open, the 5 petals curl back to reveal the yellow or greenish-yellow interior of the flower, with 5 pistils at the center arising from the 5 carpels at their bases, and with 10 surrounding stamens bearing light yellow pollen. The flowers are up to a half-inch long (12 mm).

Pollination and seeds

Both nectar-loving birds and bees are attracted to the flowers. After pollination, the flowers wither as the central teardrop-shaped carpels expand, with the crop of maturing seeds within. When ripe, the carpels split open to release the many tiny oval seeds, which are dispersed by the wind.

Plants in cultivation

Coming as it does from a Mediterranean climate, with dry summers and a winter rainy season, Tylecodon wallichii does well in places with similar climates, including our part of California. If grown in places with summer rainfall, it should be grown in a greenhouse or indoors, or with an overhead covering to keep it dry. It can endure below-freezing overnight temperatures in winter, but not sustained freezes. At the Ruth Bancroft Garden, overnight lows of 25° F (-4°C) have not harmed it. As with most succulent plants, it is important to provide it with excellent drainage. It prefers a sunny position, or at most light shade, but it is not suitable for growing in deeper shade. It should be noted that this plant is poisonous if ingested, as is also true of plants in the related genus Cotyledon.

Click here to find out more about what’s in bloom at the Garden.