General Info – summary

This small Tree with its smoothish grey, bark is often several-stemmed with visible dark lenticels and may reach 5m high. Simple Leaves have scalloped margins and are 3-5 veined from the base. Small, late opening, 5-merous, bisexual and white Flowers are regular. Distinctive long and flat-ended staminodes are present. Fruit is a capsule within the aging reddish petals that aids the wind dispersal of 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: J. E. Victor. The population is stable.

Tree

This plant is often a multi-stemmed shrub or may be a small tree up to 5m high (photo 955). The Stem (main axis of the plant, the leaf and flower bearing as distinguished from the root-bearing axis) is usually slender and has 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 – photo 957). The hairy Bark is dark brown to grey and remains relatively smooth. Unlike Dombeya rotundifolia, the bark does not becomes rough, fissured or corky. Hairy Branchlets are leafy and dark brown to grey (photo 957).

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

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

Leaves

The thinnish, round to broadly ovate Leaves are up to 7 x 5cm and are 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). These veins are slightly sunken above, slightly protruding below and each ends in a scallop at the leaf Margin. The margin is scalloped (having the margin marked with segments of circles – usually less than a semi-circle – photo 952). The Blade is usually dark green above and only slighter lighter below. Both sides of the leaves are pubescent (with dense fine, short, soft hairs, downy). The slender Petiole (leaf stalk) is up to 5cm long and has star shaped hairs. Stipules (basal appendages of the petiole) have a tail-like appendage (just visible in photo 950). The leaves are similar but smaller than those in D. rotundifolia.

: 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 on slender hairy pedicels (stalks of single flowers – photo 934 & 138) and develop in leaf axils with the new leaves. Flowers are similar to Dombeya rotundifolia but are smaller – up to 1,5cm in diameter. They also 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, and often extend beyond, the mature leaf axils at the ends of branches. Here they appear with an impressive 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). 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, creamy 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 up to 3mm wide. The Style is branched. (Mar-Jun).

: 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 138 above). The small, almost spherical fruit is a 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 loculicidally dehiscent capsule develops in the centre of the flower (photo 135). Star-like hairs (hand lens) cover the fruit. The remains of the brown, drying 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 is 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, bush and stream banks e.g., in Blyder River, Mashishing (Lydenberg), Ohrigstad (north of Mashishing), Abel Erasmus Pass, Kruger NP and the Olifants river gorge.