T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Cytisus proliferus (Tree Lucerne)

Kingdom: Plantae
(Unranked): Angiosperms
(Unranked): Eudicots
(Unranked): Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Tribe: Genisteae
Genus: Cytisus
Species: C. proliferus
Binomial name: Cytisus proliferus
Synonyms: Chamaecytisus palmensis, Chamaecytisus proliferus, Cytisus palmensis.
Common name: Tree Lucerne, Tagasaste

Cytisus proliferus is a small spreading evergreen tree that grows 3-4m high. 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 a fodder crop. It can be found in waste areas and along roadsides. 
It 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. Tree lucerne is considered to be a promiscuous legume. It will nodulate with a wide range of rhizobia.

Tree Lucerne is suited to sandy, well-drained soils of pH range 5-7. On deep, freely drained soils its roots can extend down to at least 10 metres. It will tolerate winter temperatures as low as -9°. Tree Lucerne leaves will be burnt by frost and seedlings can be killed at temperatures below 0°C. The growth of mature trees will slow at winter temperatures below 20°C. Tree Lucerne can tolerate temperatures up to 50°C, but above 36°C leaves close up from stress.
Tree Lucerne 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 11/2 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 Tree Lucerne to keep extracting nutrients from the shallow soil which would otherwise be too dry. This hydraulic lift is also seen in the banksii shrubs which have a similar root design.

Tree Lucerne can be used as a fodder crop and it is a favourite food of the New Zealand native wood pigeons.



New leaves.

The under-surface of a leaf.

Thanks to Wikipedia for text and information: