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Volume IV (1988) - Flora of New Zealand Naturalised Pteridophytes, Gymnosperms, Dicotyledons
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Polygonaceae

POLYGONACEAE

Herbs, shrubs, less commonly trees, erect or sometimes climbing. Stem nodes often swollen and jointed. Lvs usually alternate, simple. Stipules mostly forming a membranous or scarious ochrea (sheath). Infl. primarily racemose, spicate or paniculate, sometimes with secondary whorls or fascicles, usually many-flowered. Fls small, ⚥ or unisexual, actinomorphic. Perianth 3-6-merous, in 1-2 whorls, often unequal, imbricate, free or connate, often persistent and accrescent. Corolla 0. Stamens (2)-6-9-(16); filaments free or united at base. Ovary superior, sessile, 1-locular, with a solitary, basal, erect ovule. Style 2-4-branched or styles free. Fr. a 3-angled, or 2-sided biconvex nut, often enclosed in persistent, commonly winged perianth. Seed with abundant mealy endosperm.

Key

1
Perianth segments (4)-5-(6), erect, equal or subequal, unarmed and not markedly accrescent in fr. except if perianth succulent
2
Perianth segments nearly always 6 or more, generally unequal, the outer deflexed and sometimes spiny in fr., the inner strongly accrescent and enlarged and dry or nearly so
7
2
Stems prostrate to erect, rarely climbing; fruiting perianth dry, and if stems climbing then segments orbicular
3
Stems climbing; fruiting perianth succulent, or if dry then segments various but always longer than wide, not orbicular
6
3
Achene well-exserted from perianth
FAGOPYRUM
Achene not or scarcely > perianth
4
4
Thicket-forming, rhizomatous, dioecious perennials with tall stout annual stems; perianth keeled in fr.
REYNOUTRIA
Annual or perennial herbs, occasionally rhizomatous, sometimes forming large clumps, or if thicket-forming then plants ⚥; perianth lacking a raised ridge or keel in fr.
5
5
Styles deciduous, not becoming hard and rigid, straight or curved to apex
POLYGONUM
Styles persistent, becoming indurate, hooked at apex
ANTENORONζ
6
Fruiting perianth keeled, dry; fls ⚥
FALLOPIA
Fruiting perianth evenly convex and not keeled outside, succulent or if ± dry, then fls unisexual
MUEHLENBECKIA†
7
Lvs with palmate venation, usually lobed, very large; stamens (6)-9
RHEUM
Lvs with pinnate venation, sometimes veins obscure, entire to lobed, small to large; stamens 4-6
8
8
Fr. not spiny
RUMEX
Fr. with 3 rigid spines on outer perianth segments
EMEX

c. 32 genera, 800 spp., mostly N. temperate regions, also in S. temperate and subtropical regions.

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