General Info – summary

This plant may be a small to 2m high Tree or a much-branched shrub.  It is one of the smaller Calpurnia species.  Soft, light green Leaves are imparipinnate with overlapping leaflets.  Small, attractive yellow, 5-merous, zygomorphic Flowers are pea-like and develop in pendulous racemes.  The green calyx contrasts with the yellow/orange petals.  Each Fruit develops into a small grey pod that is restricted between seeds.

Description

Calpurnia sericea

Previous Names: Calpurnia intrusa, Calpurnia obovata var. pubescens, Calpurnia mucronulata, Calpurnia obovate.

SA Tree No. 219.4.

Common names:  (Afr) Berggeelkeur, Berg-geelkeur.  (Eng) Mountain Calpurnia, Mountain Wild Laburnum.

Family: Fabaceae, Leguminosae (Pea, bean or legume family).  After the Orchidaceae and the Asteraceae, the Fabaceae is the third largest Angiosperm (flowering plants) family with 700+ genera and close to 20 000 species.  Local Tree genera on this website include Acacia (Vauchellia, Senegalia), Albizia, Bauhinia, Bolusanthus, Burkea, Calpurnia, Colophospermum, Cordyla, Cyclopia, Dichrostachys, Erythrina, Erythrophleum, Faidherbia, Indigofera, Mundulea, Peltophorum, Philenoptera, Piliostigma, Schotia and Xanthocercis.  The Fabaceae are recognisable by their fruit and by their pinnately compound Leaves.  Leaves may also be simple – even bilobed and usually have stipules – some of which may be spinescent.  Leaflets are usually entire.  Flowers are bisexual and bracteate.  Regular flowers usually have 4-5 sepals and the same number of petals.  Irregular flowers have 4-5 sepals and 5 or less petals.  Stamens have anthers that have 2 pollen sacs and there are usually at least twice the number of stamens as petals – often 10.  The superior Ovary has one locule that may contain 1 or more ovules.  The Stigma and Style are simple.  The single carpel develops into the Fruit, which is usually a pod.  This pod dehisces on both sides and may break into segments.  Seeds vary.

Name derivation: Calpurnia Named after Calpurnius whose poetry was considered an imitation of Virgil’s.  Calpurnia was also the last wife of Julius Caesar.  sericea – silky: referring to the straight hairs on some of the leaves.  There are approximately 7 species of the genus Calpurnia in southern Africa.

Conservation: National Status: L C. (Least Concern).  Assessment date: 2005 (W. Foden and L. Potter).

Tree

Occasionally a small Tree, this plant may reach 2m in height.  However, it is usually a much-branched shrub (photo 382).  Young stems are usually hairy.

Leaves

Each alternate (photo 910) Leaf is up to 17cm long and is imparipinnate (pinnately compound leaf ending in a single leaflet – photo 233).  In addition to the terminal Leaflet, each leaf has up to 16 usually opposite pairs of usually hairy (photo 236) leaflets that are entire (with a continuous margin, not in any way indented).  The broadly overlapping leaflets (photo 236) are ovate/obovate to elliptic to almost round and up to 3,5 x 1,7cm.  The Apex tapers and is occasionally mucronate (ending abruptly with a distinct hair like tip – photo 236) or it might be rounded.  The Base is round to slightly lobed (photo 236).  The hairy Petiole (leaf stalk – photo 233) is up to 2cm long.  Hairy Petiolules (stalks of leaflet) are much shorter (photo 236).  Stipules (basal appendage of the petiole) are slightly more than 1mm long.  Stipels (secondary stipule situated at the base of a leaflet of a compound leaf) are absent.

Flowers

Typically, up to 100 pea-shaped Flowers develop in reasonably erect or pendulous Racemes {a simple, unbranched, indeterminate inflorescence with pedicellate (stalked flowers) along the axis that open in succession towards the apex – photo 108}.  Flowers are small – usually less than 1,2cm long.  They are bisexual and zygomorphic (irregular flower with the corolla divisible into 2 equal halves in one plane only).  The hairy green Calyx is 5-lobed, with the lobes emerging from a joined base (photo 108).  There are 5 unequal golden yellow or orange Petals (photos 108 & 380).  Red pollinator guides are visible on mature flowers on the uppermost Vexillum (standard petal – photo 380).  In this photo, the partly centrally divided vexillum petal is visible.  On this petal, red pollinator guides are visible on mature flowers (photo 380).  This petal overhangs the two Wing petals (photo 108) and these surround the lowermost pair of joined Keel petals (photo 380).  There are 10 Stamens with partly fused filaments and Anthers that are small and oblong (photo 380).  There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma).  The superior, stalked Ovary contains several ovules.  There is a single arcuate (shaped like a bow – curved) Style that ends in a single Stigma with a small head.  (Dec-Jan).

Fruit

The initially green Fruit develops into a short flat Pod that is up to 5 cm long and is restricted between seeds (photo 226).  The mature pod is narrowly winged on 1 side and ends with the remains of the style. Below each pod, the remains of the calyx are visible.

Distribution & Ecology

This plant is most common up to an altitude of 2 000m and occurs in grasslands, close to running water, and in river valley floodplains.  It is endemic in southern Africa (Endemism is the ecological state of a species being unique to a defined geographic location).  These plants are naturally located in the Eastern Cape, KwaZulu-Natal, Lesotho, Eastern Free State, Gauteng, southern Mpumalanga and in Swaziland.  They are often associated with Leucosidea sericea (ouhout) and Buddleja sp.

Ethnobotany

This is an attractive garden plant, which can easily be propagated from seeds.  It flowers best when situated in full sun.

References

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.

Foden, W. & Potter, L. 2005. Calpurnia aurea (Aiton) Benth. subsp. aurea. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2022/11/05.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.

Andrew Hankey. Help with ID.

 

http://posa.sanbi.org/flora/browse.php?src=SP

https://clarensnews.co.za/calpurnia-sericea/