Family Alzateaceae

Alzateaceae S. Graham

~ Crypteroniaceae, Lythraceae etc.

Habit and leaf form. Small trees, or shrubs (up to 20 m, with opposite or verticillate branches, these purple-red before peeling to become red-brown with age). (Hemi-) epiphytic, or self supporting. Mesophytic. Leaves opposite, or whorled (mostly clustered at the branch tips); flat; more or less leathery; shortly petiolate to sessile; not gland-dotted; simple. Lamina entire; oblong, or ovate, or obovate; pinnately veined (brochidodromous). Leaves stipulate. Stipules intrapetiolar (axillary). Lamina margins entire.

Leaf anatomy. Stomata present; anomocytic (to almost cyclocytic). Hairs absent.

Adaxial hypodermis present. Lamina dorsiventral. The mesophyll with sclerencymatous idioblasts (these branched); containing calcium oxalate crystals. The mesophyll crystals druses.

Stem anatomy. Young stems tetragonal (at first), or cylindrical (subsequently). Cork cambium present; initially deep-seated (next to the perivascular sclerenchyma). Nodes tri-lacunar (with three traces). Primary vascular tissue in a cylinder, without separate bundles; bicollateral. Cortical bundles absent. Medullary bundles absent. Internal phloem present. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem without fibre tracheids; with libriform fibres (septate). Vessel end-walls oblique; simple. Vessels with vestured pits. Wood parenchyma scanty paratracheal.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, or in panicles. Inflorescences axillary (at the ends of the branches). Flowers ebracteolate; small; regular; 5 merous; cyclic. Free hypanthium present (short). Hypogynous disk present; intrastaminal.

Perianth sepaline; 5; 1 whorled; petaloid; persistent. Calyx 5; 1 whorled; polysepalous (on the hypanthium); regular; fleshy (becoming leathery); persistent; valvate.

Androecium 5. Androecial members free of the perianth (on the hypanthium); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; alternisepalous (i.e. alternating with the members of the single perianth whorl); filantherous (the filaments short and stout). Anthers dorsifixed; introrse; tetrasporangiate (the bisporangia horizontal on the broad terminal end of the anther on either side of the connective); massively appendaged. The anther appendages apical and dorsal (by dorsal enlargement and apical extension of the connective). Anther wall of the ‘dicot’ type. Pollen shed as single grains. Pollen grains aperturate; 6 aperturate; colpate and colporate (tricolporate, with subsidiary colpi); 2-celled.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; partly inferior (the floral tube hemi-epigynous). Ovary 2 locular (Graham 1984: previously interpreted by Lourteig (1965) as becoming falsely bilocular via false septa). Gynoecium shortly stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; capitate. Placentation parietal. Ovules 30–50 per locule (‘many’); horizontal; in two rows to each of the two placentas; bitegmic. Outer integument not contributing to the micropyle. Embryo-sac development Allium-type.

Fruit non-fleshy; dehiscent; a capsule (indurated, compressed). Capsules loculicidal. Seeds non-endospermic; winged (the wing membranous, encircling the seed). Embryo well differentiated. Cotyledons 2. Embryo straight (central). Testa black.

Physiology, biochemistry. Ellagic acid present.

Geography, cytology. Neotropical. Tropical. Tropical New World.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid II. APG 3 (2009) Order: Myrtales.

Species 1. Genera 1; only genus, Alzatea.

Graham 1984, Tobe and Raven 1984.

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