Cryptostegia grandiflora
| Cryptostegia grandiflora | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Cryptostegia grandiflora |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Cryptostegia grandiflora | ||||||||||||
| R.Br. |
Cryptostegia grandiflora (in German sometimes also referred to as Indian rubber wine ) is a species of plant fromthe dog poison family (Apocynaceae). Originally from Madagascar , it hasproven to beahighly invasive neophyte in Australia .
description
Appearance and foliage leaf
Cryptostegia grandiflora is a perennial, woody liana . It can also grow as a richly branched shrub that reaches heights of 1 to 3 meters. However, if it is possible to hold on to other vegetation, their stem axes can reach up to 30 m in length. Their roots can reach a depth of 12 meters. The gray-brown, smooth bark has warty points ( lenticels ). The shoot axes come in two forms: On the one hand, as leafy branches, on the other hand, as sparsely leafed, whip-like shoots that seek support in neighboring vegetation. If the parts of the plant are damaged, a whitish milky sap escapes .
The oppositely arranged, bare leaves are divided into a petiole and a leaf blade. The reddish-purple petiole is 5 to 20 mm long. The simple, thick, leathery leaf blade is egg-shaped or oblong with a length of 3 to 10 cm and a width of 2 to 6 cm. The upper side of the leaf is glossy dark green and the underside of the leaf is slightly lighter and more matt. The leaf margin is smooth or slightly wavy.
Inflorescence and flower
At the ends of the branches there are several flowers in groups on a thick, only 4 to 8 mm long inflorescence stem. The large, showy flowers are hermaphroditic. The five broad petals are fused together to form a trumpet-shaped crown that is 4 to 6 cm long and 5 to 9 cm in diameter. The crown is light purple to whitish and usually lighter in the middle.
Fruit and seeds
There is always a pair of legume-like fruits facing each other. With a length of 10 to 15 cm and a diameter of 2 to 4.5 cm in cross section, the somewhat triangular fruit is greenish to brownish and contains 200 to 450 seeds. The brown, 5 to 10 mm long and 1.5 to 3 mm wide, flat seeds have silky white hairs 18 to 40 mm long at one end.
Distribution and ecology
Cryptostegia grandiflora is native to dry forests and grasslands of subhumid to subarid, south-western Madagascar in the provinces of Antsiranana , Fianarantsoa and Toliara .
It can now be found in many other tropical and subtropical areas. It was introduced there because of its attractive flowers on the one hand, but also because of its white milky sap, which contains high-quality, commercially usable gum, on the other. Today it grows in the Caribbean region as well as in East Africa , Mauritius , India , Southeast Asia , Latin America , the southern USA , Fiji , New Caledonia and Australia .
The seeds germinate after the first rainfall of the rainy season . If enough moisture is available, the plant can grow up to 5 meters within a month. Flowers are usually formed after the end of the rainy season. The seeds are spread by both wind and water. This species prefers areas with annual precipitation between 400 and 1400 mm and is well adapted to a monsoon climate .
Problem type in Australia
The fact that Cryptostegia grandiflora shows the greatest vegetative growth with annual rainfall of 1700 mm, but forms the richest seeds with annual rainfall of 400 mm and below, apparently predestines it for areas with extremely variable rainfall and sudden heavy rainfall events. These conditions are particularly true in central Queensland . Here it appears massively as a problem plant and is sometimes regarded as the worst weed in Australia ("Weed of National Significance").
A potential area is assumed for this plant species in Australia that extends from Coen on the Cape York Peninsula to Port Hedland in Pilbara , but so far it has not extended far beyond Queensland. It poses a major threat to gallery forests along rivers in Northern Australia as it "strangles" trees and causes them to die by stealing light. It has the same effect in forest savannahs along watercourses. This can lead to a considerable reduction in biodiversity .
The attempt to bring this plant species under control has led to natural enemies being introduced to Australia from their original habitat in Madagascar for the purpose of biological control (since the affected areas are often very remote, mechanical or chemical control attempts are hardly an option). The most important plant pest is the rust fungus Maravalia cryptostegiae . In some areas around Charters Towers this fungus infected most of the plants; however, this is not enough to stop the further spread to the west. The butterfly Euclasta whalleyi , whose caterpillar is also a predator , was introduced earlier (1988), but it proved to be ineffective.
Poisonous effect
Cryptostegia grandiflora is highly toxic to farm animals such as cows, sheep and goats. Less than 10 g of their leaves can kill a 400 kg horse in 6 days. However, it is not very palatable to cattle, so deaths usually only occur in dry seasons when there is little grass. Cardiac glycosides contained in the plant are responsible for the toxic effects .
Systematics
The valid first description of Cryptostegia grandiflora by Robert Brown in the Botanical Register; consisting of colored ... , 5, 1820, plate 435 based on the invalid publication of Nerium grandiflorum Roxb., nom. nud. in after-school care. Beng. , 1814, p. 19. It is the type species of the genus Cryptostegia .
Cryptostegia grandiflora was formerly part of the silk plant family (Asclepiadoideae). In Madagascar there is another, very similar species of this genus, Cryptostegia madagascariensis . Crossings are possible.
There are two varieties of Cryptostegia grandiflora :
- Cryptostegia grandiflora R.Br. var. grandiflora
- Cryptostegia grandiflora var. Tulearensis Costantin & Gallaud
swell
- Australian Government Information: Department of Sustainability, Environment, Water, Population and Communities. (Section Description and Problem Type)
Individual evidence
- ↑ a b Entry in the Flora of Madagascar .
- ↑ Cryptostegia grandiflora at Tropicos.org. Missouri Botanical Garden, St. Louis
