General Info – summary

This small Tree with its smoothish grey, bark is often several-stemmed with visible dark lenticels & is up to 5m high. Simple Leaves have scalloped margins & are 3-5 veined from the base. Small, late opening, 5-merous, bisexual & white regular Flowers open with leaves. Distinctive long and flat-ended staminodes are present. Fruit is a capsule within the aging reddish petals that aid the wind dispersal of the tiny seeds.

Description

Dombeya autumnalis

SA Tree No. 468.

Common names: (Afr) Rotsdrolpeer. (Eng) Autumn Dombeya, Autumn wild Pear, Rock Dombeya, Rock Wild Pear.

Family: Malvaceae: (Wild Pear, Gossypium – cotton, baobab and Hibiscus family). This family has about 240 genera and 4 200+ species. Indigenous genera that have trees on this website includes Adansonia (baobab), Cola, Dombeya, Grewia, Hibiscus, Sparrmannia and Sterculia. The usually alternate Leaves of all members possess stipules and apart from Adansonia, remain simple. Flowers are regular, bisexual or unisexual and have 5 petals (Sparrmannia africana has 4). Petals are absent in Cola and Sterculia. There are 5 to many stamens with filaments often united into a staminal tube. This surrounds the superior Ovary with its simple Style and capitate or lobed Stigma. Fruits are usually nuts, schizocarps or loculicidal capsules.

Name derivation: Dombeya after J. Dombeya a French botanist who worked in Brazil and Chile. There are more than 220 species in the genus Dombeya, 8 of which occur in southern Africa. autumnalis – referring to the flowers which open in autumn.

Conservation: National Status: L C. (Least Concern). 2005. Assessor: 2021/10/29. J. E. Victor. The population is currently stable.

Tree

This plant is often a multi-stemmed shrub or a small tree and is usually up to 5m (photo 955) but may reach 10m high . A small, rounded crown is present. The usually slender and several stemmed plant, never becomes rough, fissured or corky – unlike Dombeya rotundifolia. Clearly visible dark raised Lenticels (a usually raised corky, oval or elongated area on the plant that allows the uncontrolled interchange of gases with the environment) are present – photo 957. Hairy Branchlets are leafy and dark brown to grey (photo 950 under Leaves).

: 955. 2018/03/01 Pretoria NBG. Photo: David Becking.

: 957. 2018/03/01 Pretoria NBG. Photo: David Becking.

Leaves

The thickish, round to broadly ovate (shape of an egg with the widest point closest to the petiole – leaf stalk) Leaves are up to 1,3 x 5cm and similar but smaller than those in Dombeya rotundifolia. Leaves are deciduous and simple (have a single blade that may have incisions that are not deep enough to divide the leaf into leaflets). Stellate (star-shaped) hairs are present on both surfaces. The Apex is rounded to broadly tapering. The Base is cordate (heart shaped) to rounded and 3-5 Veined (usually 5) from the base (photo 952). The veins are slightly sunken above, slightly protruding below and all vein end in distinct scallops (having the margin marked with segments of circles – usually less than a semi-circle – photo 952) at the leaf Margin. Net veining is indistinct. The Blade is usually dark green above and only slightly lighter below (photo 952). Both sides of the leaves are pubescent (with dense fine, short, soft hairs, downy). The slender Petiole (leaf stalk) is usually up to 3cm long and has stellate hairs. Stipules (basal appendages of the petiole) have a tail-like appendage (just visible in photo 950).

: 950. 2018/03/01 Pretoria NBG.. Photo: David Becking.

: 952. 2018/03/01 Pretoria NBG. Photo: David Becking.

Flowers

The small, usually sweet-scented Flowers are borne in prefusion on green slender hairy Pedicels (stalks of single flowers – photo 934 & 138) and usually up to 15mm long. Flowers develop in leaf axils with the new leaves. Flowers are similar but smaller than Dombeya rotundifolia. They are up to 1,5cm in diameter and open much later – from late summer to autumn. This is a distinctive difference. Flowers occur in Cymes (broad, more or less flat-topped, determinate flower cluster, with central flowers opening first). Floral Bracts are initially present (photo 942). They are caducous (an organ or part that is easily detached and shed early). Flowers occur in mature leaf axils at the branch ends. Here they appear with an almost simultaneous display (photo 956). The flowers are bisexual and actinomorphic (Regular, symmetrical. Flowers are vertically divisible into similar halves by more than 1 plane passing through the axis). Unlike Dombeya rotundafolia, the Calyx is rounded and the 5 Sepals, with reflexed lobes (photos 934 & 942), are joined at the base. Sepals are externally pubescent (hairy). The Corolla contains 5 persistent, white, overlapping Petals (photo 131). There are usually 15 Stamens united at the base into a short tube – in groups of 3-8. The Filaments are of different lengths (photo 942). The Anthers are oblong with parallel Theca (pollen sacs – microsporangia of an anther. They produce microspores – pollen grains in seed plants). The stamens alternate with 5 narrowly linear Staminodes (sterile stamens – photos 939 and 942). These are slightly longer than the stamens, lack anthers and have white, broad, flat ends (photo 942). There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma). Dense fine, short, soft hairs – not bristles, cover the 3-5-locular, superior Ovary, (photo 939) which is initially up to 3mm wide. The Style is branched. (Summer-Autumn).

: 956. 2018/03/01 Pretoria NBG. Photo: David Becking.

: 934. 2018/03/01 Pretoria NBG. Photo: David Becking.

: 939. 2018/03/01 Pretoria NBG. Photo: David Becking.

: 942. 2018/03/01 Pretoria NBG. Photo: David Becking.

: 131. 2018/03/14 Pretoria NBG. Photo: David Becking.

: 138. 2018/03/14 Pretoria NBG. Photo: David Becking.

Fruit

With the development of the Fruit, the petals change to a cinnamon red colour (photo 135). The small, almost spherical fruit is a loculicidally dehiscent Capsule (a dry fruit resulting from the maturing of a compound Ovary, which usually opens at maturity by one or more lines of dehiscence). The capsule develops at the centre of the flower (photo 135). Here the initially yellowish star-like hairs cover the fruit and the remains of the stamens and style are also visible. The dry persistent petals (photo 135) aid the wind dispersal of the seeds. (Apr-Jul).

: 135. 2018/03/14 Pretoria NBG. Photo: David Becking.

Distribution & Ecology

This plant is Endemic (endemism is the ecological state of a species being unique to a defined geographic location) in South Africa. It often occurs on dolomite (dolomitic rock is sedimentary – deposited with the aid of water. The rock is made up of the mineral dolomite . The trees occur in Limpopo e.g., Sekhukhuneland, and Mpumalanga on wooded hillsides, bushveld, open woodland and stream banks e.g., in Blyder River, Mashishing (Lydenberg), Ohrigstad (north of Mashishing), Abel Erasmus Pass, Kruger NP and the Olifants river gorge. Firewood collection around informal settlements is becoming a problem.

Ethnobotany

These plants grow readily from seed. Until they are ready to be transplanted, the germinated seeds should be kept moist and away from excess heat. The smaller leaves, different flowering times and flowers and leaves produces simultaneously helps to distinguish this plant from Dombeya rotundifolia.