Grevea
| Grevea | ||||||||||||
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Male inflorescence of Grevea madagascariensis |
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| Scientific name | ||||||||||||
| Grevea | ||||||||||||
| Baill. |
Grevea is a plant genus of the family montiniaceae . It consists of three or four species and is native to Africa and Madagascar .
description
Vegetative characteristics
Grevea are deciduous shrubs or trees that reach a height of up to 5 m. Rarely grows Grevea bosseri also liana shape . The plants often form dense thickets through root saplings. The branches are corky , the entire plant is hairless with the exception of tufts of hair in the leaf axils.
The stipule-less foliage leaves are opposite or sometimes almost opposite. They are simple, with entire margins, pinnately veined and give off a strong, peppery odor when rubbed. The shape of the leaf blade is elliptical to ovate, the length is between 3.5 and 23.5 cm, the width between 1.4 and 14.0 cm. The leaves are sharply pointed towards the front, the base is narrowed to broadly wedge-shaped. The leaves often turn black as they dry.
Inflorescences and flowers
The Grevea species are dioecious separate sexes ( diocesan ). In the axils of young leaves, up to eight male flowers stand together in zymous inflorescences . The female flowers are terminal and solitary. The flowers are three or four, rarely five-fold. The sepals are fused to form a calyx, which is cup-shaped in male flowers and long tubular in female flowers. The calyx lobes are cut off to tooth-shaped. The petals stand free, overlap like a roof tile and start below the edge of the circular, nectar- producing flower base .
There is only a circle of free, fertile stamens in the same number as the petals and they stand between them, they start below the edge of the flower base. The stamens are short, the anthers bilobed and pointing outwards. They open through longitudinal slits. Instead of the stamens, only staminodes are formed in the female flowers . The ovary is inferior, completely or partially zweikammerig and contains four to twelve ovules . The stylus is terminal and has two lobes at the tip, the scars are on the inside of these lobes.
Fruits and seeds
The large, dry capsule fruits are brittle but do not crack open. The ovary with the two scar lobes is permanent and stands at the pointed tip of the fruit. The base is narrowed, remnants of the calyx and the flower base remain. The surface of the fruit is slightly ribbed and smooth or provided with white bumps. The spherical or indented, reddish or yellowish-brown colored seeds contain plenty of endosperm .
Occurrence
The genus occurs in eastern Africa and Madagascar . The Malagasy deposits are located in the dry, deciduous forest in an area north of Morondava to Antsiranana . The genus is particularly common there in the Ambongo area south of Mahajanga .
Systematics
- Grevea bosseri Letouzey
- Grevea eggelingii Milne-Redh.
- Grevea madagascariensis Baill.
literature
- George E. Schatz: Generic Tree Flora of Madagascar. Royal Botanic Gardens et al., Kew 2001, ISBN 1-900347-82-2 .
- Bernard Verdcourt: Montiniaceae (= Flora of Tropical East Africa. ). Royal Botanic Gardens et al., Kew et al. 1973, ISBN 0-85592-026-2 .
