Vitex lucens Kirk

국표에 없다.

Vitex lucens, or pūriri, is an evergreen tree endemic to New Zealand.

History

Pūriri was first collected (by Europeans) at Tolaga Bay by Banks and Solander during Cook's first visit in 1769. The plant was excellently described by Solander in his manuscript "Primitae Florae Novae Zelandiae" under the name Ephielis pentaphylla, and a drawing of considerable artistic merit was also prepared. The next botanist to notice pūriri, Allan Cunningham, did not do so until 1826 when he observed it on "the rocky shores of Bay of Islands, growing frequently within the range of salt water." Cunningham named it Vitex littoralis, correctly assigning it to the genus Vitex but overlooking that "littoralis" had been used for a Malayan species 4 years earlier. Thomas Kirk proposed V. lucens in 1897 after attention had been drawn to the fact that V. littoralis was taken.

The Māori name of this tree is pūriri or sometimes kauere. 'New Zealand mahogany' and 'New Zealand teak' occur in older printed sources, especially in reference to the timber.

Description

The pūriri tree can grow up to 20 m tall, with a trunk commonly up to 1.5 m in diameter, frequently thicker, and a broad spreading crown. The thin bark is usually smooth and light brown in colour, but can also be very flaky. Pūriri was actively and selectively logged in the past to provide timber for a wide range of end uses. Only the best trees were felled, leaving the gnarled pūriri often found on farm paddocks. This has given the impression that pūriri is incapable of growing straight, but early reports of pūriri describe naturally clear boles of 15 to 30 feet (4.5 to 9 m) and there are still a few trees like that left. A good example of a well-shaped tree is behind Ruapekapeka Pā in Northland.

The dark green glossy leaves of pūriri are palmate with usually 5 leaflets, or sometimes three. The lowest two leaflets are smaller than the other three. The leaflets have domatia, little pockets where the mid vein and branching veins meet, which can house arthropods. The underside and veins are a lighter green. Seedling leaves are much more delicate and a lighter green with serrations along the edge. Seedling pūriri can be confused with seedlings of the kohekohe, or Dysoxylum spectabile; the most obvious difference is that pūriri leaflets originate from one point, whereas kohekohe leaflets are spread along the stalk. The branches of pūriri, especially the young ones, are square in cross-section.

A large pūriri near Ruapekapeka, Northland

Pūriri is one of the few native trees with large colourful flowers. Many plants in New Zealand have white or green flowers. The tubular flowers of the pūriri look rather like snapdragon flowers and can range from fluorescent pink to dark red, rose pink (most common) or sometimes even to a white flower with a yellow or pink blush. The bright colour, the tube shape, copious nectar production and the hairs at the base of the flower tube all point towards birds pollinating this flower (the hairs stop insects from stealing the nectar). On the New Zealand mainland there is often plenty of nectar in the flowers because there aren't enough birds to eat all the nectar produced by the tree.

The flower has 4 lobes (made of 2 petals), 4 long stamen (the male part of the flower) and the style grows to be as long as the stamen after the pollen has shed. It is interesting to see how the flowers open. The petals overlap each other in the bud form. The growing stamen push the petals open. When the flower is fully open the style starts growing and reaches its full length just after the anthers on the stamen have shed all the pollen. The flowers occur in loose clusters of up to 12 flowers per cluster.

Some flowers can be found on the pūriri all year round, though it does flower most heavily over winter. Ripe fruit can also be found all year round, but is more common over the summer. Pūriri is a very important tree for native birds in the top half of the North Island because it provides a constant year-round food supply. Flowers and fruit are carried at the tips of the branches.

The fruit or drupe is a bright red (usually) to a pale yellow (rarely, and only on white flowered trees) "cherry". It can grow as big as a cherry, but it is unpleasantly astringent. When broken, the fruit has a bright thin juice, and a faint grape smell. Pūriri fruit is not the most nutritious sort in the New Zealand bush (high in carbohydrates, not lipids, sugars or calcium), but it is always there. The nut (endocarp) inside the drupe is a very hard pear-shaped kernel that can contain up to 4 seeds. The seedlings from one kernel can germinate at the same time or be spread over a year. The nut has four apertures in the endocarp each guarded by an oval door and each leading to a seed chamber. The Pūriri is self-fertile with self-fertilization (autogamy) possible. Seed production in 12 samples ranged from 8% to 45% with usually only 1 or 2 live seeds in a fruit. Low seed production is due to inefficiencies in pollination, as well as breakdown of apparently fully developed seeds. The factors controlling germination and opening of the doors are unknown, and most seed would appear to perish within the Imprisoning nut.

https://youtu.be/kgIBHl-eriE?t=338