Atherospermataceae

Laurelia sempervirens

The Atherospermataceae are a plant family of the order of the laurel -like ( Laurales ).

• 4.1 Notes and references
• 4.2 Literature

Features

Habit and stem

The Atherospermataceae are trees or shrubs. The Secondary growth in thickness is normal. The nodes are unilakunär with a leaf-trace strand. The sieve tube plastids are P-type I ( a).

The leaves are opposite, petiolate, without stipules. They are simple and aromatic. The leaf margin is coarsely toothed, sometimes with glands on the teeth. The anatomy is dorsiventral. In the mesophyll are no mucous cells. The stomata are paracytisch or anomocytisch.

Inflorescences and flowers

The flowers appear singly or in cymes. The plants are hermaphroditic, monoecious or dioecious. There are also unisexual flowers. The flowers are relatively small.

The perianth is divided into calyx and corolla, only cup-shaped or absent. When present, there are four (2 2) or six to 20 sepals in two (three) whorls. Petals, if present, are from seven to 20 in a whorl.

The androecium consists of 12 to 100 stamens in one or two whorls. There are all fertile, only in the hermaphrodite flowers of Doryphora also staminodes occur. The stamens have shed glands at the base. The anthers are adnat and open with elongated flaps that attach to the top of the theca. The pollen is di -or tri- aperturat ( sulculat ).

The gynoecium consists of three to 100 free, spirally arranged carpels. It is upper constant or sometimes slightly depressed in the receptaculum. The stylus is on the side. Each carpel has a anatrope ovule with basal placentation.

Fruits

The carpels develop similar to the achenes to dry closing fruits. The seeds have an oily endosperm. It is distributed by the wind ( Anemochorie ).

Chemical properties

In the family flavonols have been identified, kaempferol and quercetin.

The chromosome number is x = 22

Dissemination

The family comes in the temperate to tropical regions of the Southern Hemisphere: Australia, Tasmania, New Guinea, New Zealand, New Caledonia. Two genera occur in Chile.

Are the representatives of the family are important elements of the laurel forests in New Zealand and Tasmania in the temperate evergreen forests 800-2400 m above sea level in Chile.

System

The sister clan within the Laurales are the Gomortegaceae. The common features are the presence of bud scales; Siebröhrenplastiden with fibrils; the outer, not the inner stamens are converted to staminodes; and a short pen.

The family itself is monophyletic. There are seven genera with 16-22 species:

• Atherosperma Lab., Endemic to Tasmania with about five species
• Daphnandra Benth., With about seven species in New Guinea and Australia
• Doryphora Endl. , With two species in northeast Australia
• Dryadodaphne S. Moore, with about three species in New Guinea and Australia
• Laurelia Juss., With one or two species in South America and New Zealand
• Laureliopsis with only one kind in South America: Laureliopsis philip piana ( Looser ) Schodde

The genera were formerly partly provided to the Monimiaceae.

Representatives of the family are known from Antarctic forests of the Late Cretaceous / Early Tertiary. The oldest fossils are about 88 million years old. The age of the family is estimated at 88-115 million years. Individual species and genera ( Atherosperma, Laurelia novae- zelandicae ) are nearly 70 million years old.

Sources and further information

The article is based primarily on the following links:

• Atherospermataceae on the APWebsite (English )
• Atherospermataceae in L. Watson and M. J. Dallwitz (1992 onwards ), The families of flowering plants