Botanic Gardens Trust, Sydney, Australia

Plant info




Characteristics

Bud Formation

Most flowering plants, though not conifers, have dormant buds in the axils (the angles between the upper side of each leaf and the stem) - so if a plant is damaged by insects or pruning, these buds can sprout. In the genus Araucaria and in the Wollemi Pine, each axil has a small group of cells thatís somewhere between a fully formed bud and no bud at all. A unique feature of the Wollemi Pine is that these buds on upright branches develop normally to form a multi-stemmed and multi-branched tree - see appearance.

Further reading: The Wollemi Pine (Wollemia nobilis, Araucariaceae) possesses the same unusual leaf axil anatomy as the other investigated members of the family, by Geoffrey E. Burrows, Australian Journal of Botany, 4:61-68 (1999).

Coppicing

Some dormant buds may sprout along the trunk or from the base of the trunk. This is called coppicing, resulting in large old plants with multiple trunks of different ages - see age and ancestry. This may be a defence against damage from drought, fire or rock fall in the steep canyons where they grow. ItĎs probably the reason that the Wollemi Pine has survived the increasing aridity of Australia over millions of years - see ecology.

Further reading: Architecture of the Wollemi Pine (Wollemia nobilis, Araucariaceae), a unique combination of model and reiteration, by K D Hill, Australian Journal of Botany, 45: 817-826 (1997).

Branch loss

The leaves donít have stalks (petioles) to attach to the branch - see appearance. Instead, the whole base of the leaf wraps halfway round the branch. So the tree sheds entire lateral branches rather than individual leaves, which is another unusual feature it shares with the genus Araucaria.

Water loss

Its leaves have a thick cuticle (a very thin film covering the outer, or epidermis, layer of the leaf), a fibrous hypodermis (a layer of cells just under the epidermis) and sunken stomata (pores), a survival characteristic which helps it reduce water loss.

Further reading: Leaf Anatomy of Wollemi Pine (Wollemia nobilis, Araucariaceae), by Geoffrey Burrows and Suzanne Bullock, Australian Journal of Botany, 47(3): 798-806 (1999).

 

Adult leaves
Leaves of the Wollemi Pine are attached directly to the branch. 

Coppicing habit
Upright (orthotropic) branches developing from the base of a tree (self-coppicing) from a multi-trunked Wollemi Pine.

Sunken stomata
Close-up of Wollemi Pine leaf surface showing sunken stomata