The families of flowering plants.
IncludingGranateae (Granataceae) D. Don
Habit and leaf form. Small trees, or shrubs (with scattered secretory cells in the cortex and pith, sometimes spiny).Plants non-succulent. Leptocaul. Leaves alternate to opposite (sometimes crowded at the tips of the twigs); petiolate; non-sheathing; not gland-dotted; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire.
Leaf anatomy. Stomata present; mainly confined to one surface (abaxial); anomocytic.
Lamina dorsiventral; without secretory cavities. The mesophyll without sclerenchymatous idioblasts; containing calcium oxalate crystals. The mesophyll crystals druses and solitary-prismatic. Minor leaf veins without phloem transfer cells.
Stem anatomy. Young stems tetragonal (with four wings, which are soon lost). Cork cambium present; initially deep-seated. Nodes unilacunar. Cortical bundles absent. Medullary bundles absent. Internal phloem present. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Vessels with vestured pits. Primary medullary rays narrow. Wood parenchyma scantily paratracheal (or absent).
Reproductive type, pollination. Plants hermaphrodite; homostylous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’. Inflorescences terminal, or axillary; in axillary fascicles, or the flowers solitary and axillary. Flowers regular; cyclic; polycyclic (by virtue of the androecium). Free hypanthiumpresent (this brightly coloured, far exceeding the inferior ovary).
Perianthwith distinct calyx and corolla; 10–16; 2 whorled; isomerous. Calyx 5–8; 1 whorled; polysepalous (in the form of lobes on the hypanthium); regular; becoming leathery; persistent (on the persistent, leathery hypanthium); valvate. Corolla 5–8; 1 whorled; polypetalous; imbricate and crumpled in bud; regular. Petals clawed to sessile.
Androecium 30–100 (‘many’). Androecial members maturing centrifugally; free of the perianth (but inserted inside the hypanthium); free of one another; about 5–7 whorled (?), or 2 whorled (according to Graham et al. 1993). Androecium exclusively of fertile stamens. Stamens 30–100 (‘many’);polystemonous; filantherous (the filaments slender). Anthers dorsifixed; versatile; dehiscing via longitudinal slits; tetrasporangiate. Endothecium developing fibrous thickenings. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate; 2-celled.
Gynoecium 7–9(–15) carpelled. Carpels isomerous with the perianth to increased in number relative to the perianth. The pistil 7–9(–15) celled. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary 7–9(–15) locular. Epigynous disk present. Gynoecium stylate. Styles 1; apical (slender,simple). Stigmas 1; capitate; wet type; papillate; Group III type. Placentation axile (only, in P. protopunica), or axile and parietal (in P. granatum, where the carpels become superposed in two or three layers by differential growth, the lower with axile placentation, the upper ostensibly parietal). Ovules 20–50 per locule (‘more or less numerous’); anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3 (uninucleate); not proliferating. Synergids elongated. Endosperm formation nuclear.
Fruit fleshy; indehiscent; a berry (with 2–3 layers of locules, and a leathery rind representing the hypanthium, crowned by the persistent calyx, the seeds embedded in pulp derived from the outer layers of the testas). Seedsnon-endospermic. Embryo well differentiated (oily). Cotyledons 2; large, spirally rolled. Embryo achlorophyllous (1/1); straight.
Physiology, biochemistry. Not cyanogenic. Alkaloids present (one species). Iridoids not detected. Proanthocyanidins absent. Flavonols absent. Ellagic acid present. Saponins/sapogenins absent. Sugars transported as oligosaccharides + sucrose, or as sugar alcohols + oligosaccharides + sucrose. Inulin recorded (Gibbs 1974). C3. C3 physiology recorded directly in Punica.
Geography, cytology. Holarctic and Paleotropical. Temperate to tropical. Southeast Europe to the Himalayas, Socotra. Western and Northern Eurasia, U.S.S.R., Middle East, Mediterranean, Eastern and Southern Asia, North America, and West Indies. X = 8, 9.
Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Myrtales (as a synonym of Lythraceae).
Species 2. Genera 1; only genus, Punica.
Economic uses, etc. ‘Pomegranate’ is the berry of Punica granatum.