Cytisus proliferus
| Tagasaste | |
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Fabales |
| Family: | Fabaceae |
| Subfamily: | Faboideae |
| Tribe: | Genisteae |
| Genus: | Cytisus |
| Species: | C. proliferus |
| Binomial name | |
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Cytisus proliferus L. f. |
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| Synonyms | |
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Cytisus proliferus, tagasaste or tree lucerne, is a small spreading evergreen tree that grows 3-4m high. It is a well known fertilizer tree. It is a member of the Fabaceae (pea) family and is indigenous to the dry volcanic slopes of the Canary Islands, but it is now grown in Australia, New Zealand and many other parts of the world as fodder crop.
Tagasaste is an evergreen shrub that has rough yellow-grey bark and velvety hairy young growth. Its leaves are composed of 3 greyish-green equal-sized leaflets, which are slightly paler on the underside. Its scented, creamy-white flowers form in small clusters in the leaf axils. Its flat pea-like pods are green, ripening to black. The seeds are tiny (45,000/kg), shiny and black. Tagasaste is considered to be a promiscuous legume, compatible with cowpea and Tagasaste 1502 Rhizobium. It will nodulate with a wide range of rhizobia.
Tagasaste is suited to sandy, well-drained soils of pH range 4–7. On deep, freely drained soils its roots can extend down to at least 10 metres. Any physical or chemical barrier in the soil that restricts root growth will reduce the productivity and survival of tagasaste. Cultivars from arid sandy areas are very susceptible to root rot fungus on poorly drained soils, specifically Fusarium, Pythium and Rhizotona. It will tolerate winter temperatures as low as −9 °C, but cultivars exist that can handle winter temperatures down to minus 15°C as in Orange, Eastern Australia. Tagasaste leaves will be burnt by frost and seedlings can be killed at temperatures below 0 °C. Growth of mature trees will slow at winter temperatures below 20 °C. Tagasaste can tolerate temperatures up to 50 °C, but above 36 °C leaves close up from stress. Tagasaste flowers during the early rainy season, typically June to October in Australia, New Zealand and East Africa.
Tagasaste has two types of roots. There are a few large 'sinker' roots that can extend down to at least 10 metres. These are used to extract moisture from that depth during the long dry summers. There are also many 'feeder' roots that are mostly confined to the top 1 1⁄2 metres. These can extend out at least 15 metres from the trunk. They extract mineral nutrients from the soil, and also water in winter. In summer the soil water can be taken up at depth by the sinker roots, drawn into the shallow feed roots and then pumped into the soil. This 'hydraulic lift' allows the tagasaste to keep extracting nutrients from the shallow soil which would otherwise be too dry. This hydraulic lift is also seen in the native banksia shrubs that grow naturally on these soils and have a similar root design.
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Wikipedia