Cotyledon gloeophylla Van Jaarsv.
Common names: sticky-leaved cotyledon (Eng.); taaiblaarplakkie (Afr.)
Cotyledon gloeophylla is an exciting, recently discovered species from the Kouga Dam near Patensie in the Eastern Cape; it is a shrublet with decorative, sticky leaves and drooping solitary reddish flowers in winter and spring, and it does well in pots.
Cotyledon gloeophylla is a much-branched shrublet up to 600 mm tall, with branches that rise upwards from a horizontal position (ascending). It has fibrous roots. The basal branch is up to 18 mm in diameter, longitudinally fissured with peeling, greyish brown bark. The leaves have no stalk (sessile), and are in opposite pairs (decussate), ascending to spreading, flat, broadly obovate, 25–50 × 20–17 mm, green, slightly leathery in the upper third and the margin reddish. The leaf surface is very sticky due to a dense covering of very short, translucent, club-shaped, glandular hairs. The base of the leaf is wedge-shaped (cuneate) and the leaf tip ends in a little point (mucronate). The leaf internodes are about 5–18 mm apart.
The inflorescence is reduced to a solitary flower at the branch ends and have one pair of bracts 5 × 1 mm, soon falling off (becoming deciduous). The peduncle is about 45 mm long. The calyx lobes are triangular, 8 × 4 mm. The flower (corolla) is pendent, about 30 mm long; the cylindrical tube, 17–18 mm long and 10 mm in diameter at base, the lobes linear-lanceolate, 17 × 5 mm, spreading and becoming recurved, fused basally for about 16–17 mm. The stamens 10, in two whorls; anthers bearing terminal appendages. Style branches free for 8 mm.
Cotyledon gloeophylla was only described in 2015, and its Red List status has not yet been formally evaluated. In the author’s opinion this species is rare and localized, but it is not threatened.
Distribution and habitat
Cotyledon gloeophylla is only known from the Kouga Dam region, growing in Gamtoos Thicket (Mucina & Rutherford 2006) on steep slopes at an altitude of about 50–300 m above sea level. The climate in its habitat is dry, subtropical with warm winters that are frost-free. Temperatures in summer can be very high with an average daily maximum of about 24–27°C, the average daily minimum about 10°C. Rainfall occurs mainly in summer, but winter rains are also experienced, ranging from 400–500 mm per annum. Plants grow among shrubs often in shade or with the protection of other shrubs. This area of the Eastern Cape is very rich in succulents. Associated succulents include Portulacaria afra, Crassula ovata, C. cultrata, C. perforata and C. rupestris subsp. rupestris, Lampranthus coralliflorus, Sterculia alexandri, Bulbine latifolia and Rhoicissus tridentata.
Derivation of name and historical aspects
Cotyledon gloeophylla was named by the author in the British Cactus & Succulent Journal, Bradleya, in 2015. It has been known for several years and grown at Kirstenbosch National Botanical Garden since September 1990, when the Kouga Dam was investigated as part of his study of the genus Gasteria. The specific epithet gloeophylla means ‘sticky leaves’ from the Greek gloia, meaning ‘glue’ and phyllon ‘leaf’, and pertains to its unusual sticky leaves.
Cotyledon gloeophylla is closely related to C. woodii, a widespread species with smaller, non sticky, green to greyish green leaves. C. gloeophylla is one of a dozen Cotyledon species growing in South Africa (Van Jaarsveld & Koutnik 2004).
The plant flowers in winter and early spring, and the tubular orange-red flowers are pollinated by local sunbirds while they feed on the nectar inside. After fertilization, the capsule matures and becomes erect, opening from the end and the fine seeds are dispersed by wind. The sticky leaves are perhaps an adaptation to prevent predation and conserve water.
Apart from its horticultural potential, it is not known to be used in other cultural aspects.
Growing Cotyledon gloeophylla
Cotyledon gloeophylla is an attractive plant with horticultural appeal. It is characterized by its decorative, sticky, flat, green leaves and pendent tubular flowers. It grows well in cultivation and does best as a containerized plant and is suitable for window sills, or it can be grown in rockeries. In cold climates where frost occurs it should rather be grown in a greenhouse under controlled conditions. It is a slow grower, but eventually forms a small branched shrublet. Cotyledon gloeophylla is best cultivated in Thicket and Succulent Karoo Gardens (Van Jaarsveld 2010), or similarly dry Mediterranean-type gardens in other parts of the world, where frost is not too severe. Plants prefer full sun to partial shade. If grown in shady conditions, the leaves tend to be larger and greener. Flowering size can be reached in about 3 to 4 years.
Cotyledon gloeophylla is easily propagated from stem cuttings or seed. Cuttings are best taken in spring or summer and rooted in a small container in a well-drained medium such as sand, but can take several weeks to root. Sow seed preferably during spring or summer in a shady position in a sandy, slightly acidic, soil. Cover with a thin layer of sand and keep moist. Best to feed plants with an organic fertilizer, compost or any other liquid fertilizer. Cotyledon gloeophylla can be watered at any time of the year, its main growing season is summer and watering should be reduced in winter.
- Mucina, L. & Rutherford, M.C. 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
- Van Jaarsveld, E.J. 2010. Water wise gardening. Struik, Cape Town.
- Van Jaarsveld, E.J. 2015. Cotyledon gloeophylla, a new species from the Kouga River, Eastern Cape. Bradleya 33: 180–184.
- Van Jaarsveld, E. & Koutnik, D. 2004. Cotyledon and Tylecodon. Umdaus Press, Hatfield, Pretoria.
Ernst van Jaarsveld
Babylonstoren Farm for Kirstenbosch National Botanical Garden
Plant Type: Shrub, Succulent
SA Distribution: Eastern Cape
Soil type: Sandy
Flowering season: Spring, Winter
Flower colour: Red, Orange
Aspect: Full Sun, Shade, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Easy