Atherospermataceae
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The Atherospermataceae are a family of plants from the order of the laurel-like (Laurales).
features
Habit and trunk
The Atherospermataceae are trees or shrubs. The secondary growth in thickness is normal. The nodes are unilacunar with a strand of leaf traces. The sieve tube plastids are of the P-type I (a).
leaves
The leaves are opposite, stalked and without stipules . They are simple and fragrant. The leaf margin is roughly toothed, partly with glands on the teeth. The anatomy is dorsiventral . There are no mucous cells in the mesophyll. The stomata are paracytic or anomocytic.
Inflorescences and flowers
The flowers are solitary or in cymes. The plants are hermaphroditic, monoecious or dioecious. There are also unisexual flowers. The flowers are relatively small.
The inflorescence is divided into calyx and crown, only calyx-shaped or absent. If present there are four (2 + 2) or six to 20 sepals in two (three) whorls. Petals, if any, are seven to 20 in a whorl.
The androeceum consists of 12 to 100 stamens in one or two whorls. They are all fertile, only staminodes occur in the hermaphrodite flowers of Doryphora . The stamens have glandular scales at the base. The anthers are adnate and open with elongated flaps that attach to the tip of the theca. The pollen is di- or tri-aperturate (sulculate).
The gynoeceum consists of three to 100 free, screw-like carpels . It is on top or sometimes slightly sunk into the receptacle. The stylus starts on the side. Each carpel has an anatropic ovule with basal placentation.
fruit
The carpels develop into dry closing fruits similar to the achenes . The seeds have an oily endosperm . It is spread by the wind ( anemochory ).
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Chemical characteristics
Flavonols , kaempferol and quercetin have been found in the family .
The number of chromosomes is x = 22.
distribution
The family occurs in the temperate to tropical areas of the southern hemisphere: Australia , Tasmania , New Guinea , New Zealand , New Caledonia . Two genera occur in Chile .
In Chile the representatives of the family are important elements of the laurel forests, in New Zealand and Tasmania in the temperate evergreen forests between 800 and 2400 m above sea level.
Systematics
The sister family within the Laurales are the Gomortegaceae . The common features are the presence of bud scales; Sieve tube plastids with fibrils; the outer, not the inner, stamens are transformed into staminodes; and a short stylus.
The family itself is monophyletic. There are seven genera with 16–22 species:
- Atherosperm Labill. , 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
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Laureliopsis Schodde with only one species in South America:
- Laureliopsis philippiana (Looser) Schodde
- Nemuaron Baill. , with one or two species in New Caledonia.
The genera used to be partially assigned to the Monimiaceae .
Members of the family are known from Antarctic forests of the late Cretaceous / early Tertiary . The oldest fossils are around 88 million years old. The age of the family is estimated to be 88 to 115 million years. Individual species and genera ( Atherosperma , Laurelia novae-zelandicae ) are almost 70 million years old.
Sources and further information
The article is mainly based on the following web links:
- Atherospermataceae on the APWebsite (Engl.)
- Atherospermataceae in L. Watson and MJ Dallwitz (1992 onwards), The families of flowering plants
Individual evidence
- ^ Susanne S. Renner : Variation in diversity among Laurales, Early Cretaceous to Present . Biol. Skr. 2004, Volume 55: pp. 441-458. ISSN 0366-3612
literature
- Richard Schodde: A monograph of the family Atherospermataceae R. Br . PhD thesis, University of Adelaide, 1969.
- David John Mabberley : The Plant Book. A portable dictionary of the higher plants . Cambridge University Press 1987. ISBN 0-521-34060-8
