Identifying Northlands Juvenile Native Trees

It is unusual elsewhere but it is common for many of new Zealand native trees to look very different as they grow up.

Some botanists suggest this growth pattern evolved to prevent Moa from eating the saplings.

These changes come in different forms.

• Juvenile plants can be much bushier (divaricating) as dense, tangled plants would be difficult to eat
• Juvenile leaves can be smaller or more fibrous making more them difficult to consume and digest.

But once grown to 2–3 metres (out of moa reach), they can

• Stop being divaricating and  grow straight single trunks and have larger and fewer branches.
  e.g Matai and kaikōmako
• Do the opposite and develop branches instead of a straight stem e.g lancewood
• develop larger leaves less fibrous which can take in more sunlight, e.g XXXXXX

changing their form in this manner means that the plants can receive maximum light at different levels in the forest.

Some vines become big trees e.g Northern Rata.

  Many New Zealand trees have different leaves as saplings and as adults. For example

leaf size can also vary with the same plant in a shady area having larger leaves than plants in full sunlight. For example m

Leaf colour can also change with more mature trees or trees in brighter sun being more brown coloured than juveniles or other in he shade. for example …

The lancewoods juvenile form has long, narrow leaves that are angled downwards around a slender stem. The adult form has much shorter, broader leaves and a densely branched, broadly rounded crown.

Adult, juvenile and a tree at an intermediate stage with both types of foliage

In many conifers, the leaves of juvenile plants differ from those of adults in size, and often also colour and form; The juvenile leaves are usually noticeably longer than the adult leaves.

The transition from juvenile to adult foliage can be gradual, with juvenile leaves progressively changing form along the branch until the adult form is reached; or it can be abrupt and without intermediates, when branches bearing one type of leaf produce lateral branches with another leaf type.

There are three main stages

1. Saplings  These  grow straight upwards with branches going out along the length of the trunk. The aim  to get as high as possible as quickly as possible in search of sunlight
2. Rickers-  This tends to happen after 30 -50 years. As the sapling gains in height, the lowest branches are shed to prevent vines from climbing plus they are shaded by those above so are of little use. The bark does not tend to flake off at this stage. The name Ricker is a naval term and because that these trees were ideal for naval masts and spas
3. Mature tree Once the tree merged above the forest canopy, does not then need to grow taller although it continues to do so. The girth of its trunk increases and its top branches spread out to support a spreading crown of leaves. The bark is very flaky.

The Northern Rata begins its life as a (hemiepiphyte) and so spends part of its life cycle as an epiphyte. The seeds germinate in the canopy and initially live epiphytically. They send roots downward, and these roots eventually make contact with the ground. over centuries these roots  grow  around the trunk of its host, eventually forming a massive, frequently hollow pseudotrunk composed of fused roots.The rata will eventually grow up to 25 metres (82 ft) or taller

The rata can also grow in open ground as a tree but has a much smaller trunk

The nïkau is very slow-growing. Research conducted in lowland forests near Auckland found it takes 40–50 years to begin to form a trunk and about 200 years to reach 10 metres tall. On average two fronds are shed per year leaving behind a leaf scar on the trunk which can be used to give a rough indication of age since the trunk began forming.