Amaranthaceae

Primary tabs

Amaranthaceae

Description

Annual or perennial herbs, subshrubs or shrubs, or clambering lianas, or trees. Leaves opposite or alternate, simple, entire or nearly so; sessile to petiolate; exstipulate. Inflorescence of cymules, spikes, racemes, thyrses, heads or panicles, often of ultimate 3-flowered cymules; flowers subtended by 1 bract and 2 bracteoles; lateral flowers of 3-flowered cymules sometimes sterile and modified into scales, spines, bristles or hairs. Flowers bisexual or unisexual, monoecious, dioecious or polygamous when unisexual, regular, hypogynous; tepals (1)3-5 (0 in female Amaranthus australis), free or shortly united below, often persistent, scarious, imbricate in bud; stamens (2-3)5, opposite tepals, anthers 2- or 4-locular, dehiscent by longitudinal slits, filaments united below in a cup, pseudostaminodia present or absent; ovary superior, 1-locular, ovules 1-ca. 20 (usually 1), placentation basal, style 1, stigmas 1-3. Fruit a dry, irregularly dehiscent capsule or utricle, rarely berry-like; seeds small, testa shining, embryo horseshoe-shaped or circular, surrounding starchy, copious perisperm, endosperm scanty.

Distribution

Guianas: present
A mostly tropical and subtropical family of approximately 1000 species in 69 genera; some weedy or cultivated as ornamental or edible plants; in the Guianas 24 species in 10 genera.

Wood

Included phloem included in tangential bands of conjunctive tissue which form a reticulate pattern with the unlignified rays.
Vessels diffuse, solitary or in small multiples, round to oval, diameter 40-150 μm, 10-30 per mm², the variation mainly due to the unlignified vesselless zones.
Perforations simple. Intervascular pits alternate, round, 7-8 μm. Vessel-ray pits simple, oval to elongated, slightly irregular. Vessel member length 300-400 μm.
Ray-like zones of mainly unlignified parenchymatic cells linking the successive layers of conjunctive tissue.
Crystal sand present in radial and tangential conjunctive tissue.
Parenchyma scantily diffuse and as narrow vasicentric sheaths; fusiform cells and strands of 1-2 cells, 200-300 μm high.
Fibres thin-walled, walls 2-4 μm, lumina up to 25 μm wide. Pits minute, simple, numerous on both tangential and radial walls.
The only species occurring in the Guianas and represented in the Utrecht wood collection is the climbing liana Chamissoa altissima. The xylem body is divided in small parts by a network, formed by unlignified ray-like zones and wide tangential bands of unlignified conjunctive tissue ().
As far as known the wood is of no commercial value.
A. Carlquist, S. - in Comparative Wood Anatomy. Systematic, Ecological, and Evolutionary Aspects of Dicotyledon Wood. 1988, B. Lindeman, J.C., A.M.W. Mennega and W.J.A. Hekking. - in Bomenboek voor Suriname. Herkenning van Surinaamse houtsoorten aan hout en vegetatieve kenmerken. 1963, C. Metcalfe, C.R. & L. Chalk., Wood structure and conclusion of the general introduction in Anatomy of the Dicotyledons vol. II. 1983, D. Record, S.J. & R.W. Hess. - in Timbers of the New World. 1943