ACKNOWLEDGMENTS The authors wish to thank Shirley C. Tucker for helpful review comments, and Kanchi N. Gandhi and Jan Kirschner for nomenclatural advice. viii
SAURURACEAE Anthony R. Brach & Xia Nian-he <strong>Saururaceae</strong> Rich. ex E.Mey., Houttuynia 20 (1827), nom. cons. Type: Saururus L. Herbs perennial, aromatic. Stems erect, ascending or prostrate, obviously jointed. Leaves alternate, simple; stipules interpetiolately connate or adnate to petiole, forming a sheath. Inflorescence a dense spike or raceme, sometimes resembling a single flower when large involucral petaloid bracts are present at base. Flowers bisexual; perianth absent. Stamens usually 3, 6, or 8, free or adnate to ovary; anthers 2-locular, longitudinally dehiscent. Pistils (2 or) 3 or 4-carpellate, rarely to 7-carpellate; carpels distinct or connate, if distinct then each carpel with 2–4 ovules, if connate then ovary unilocular, with placentation parietal and each placenta with 6–13 ovules; styles free. Fruit a schizocarp or apically dehiscent capsule. Seed(s) 1 or many; endosperm scanty; perisperm abundant; embryo minute. Four genera, six species, in temperate to tropical regions of S & E Asia and N America; three genera and four species in Asia; two genera each having one species in N America. The species of this family have been extensively compared in studies of floral vasculature (H.X.Liang & S.C.Tucker, Amer. J. Bot. 77: 607–623, 1990), organogenesis (H.X.Liang, Acta Phytotax. Sin. 32: 425–432, 1994), pollen morphology (H.X.Liang, Acta Bot. Yunnan. 14: 401–404, 1992), and stem anatomy (S.Carlquist et al., Internatl Assoc. Wood Anat. J. 16(2): 133–150, 1995). Oil cells are present throughout <strong>Saururaceae</strong>, and are the basis for the "aromatic" nature of both vegetative and reproductive organs in the family, and have been studied developmentally (S.C.Tucker, Bot. Gaz. 137: 341–347, 1976). Phylogeny within the family (S.W.Meng et al., J. Pl. Res. 115: 71–76, 2002), with its sister clade Piperaceae (S.C.Tucker et al., Syst. Bot. 18: 614–641, 1993), and another genus of early angiosperms — Nymphaea (J.-F.Leroy, Evolution 319: 543–547, 1996) has been discussed. Initially included in the <strong>Saururaceae</strong>, the genus Circaeocarpus C.Y.Wu (Acta Phytotax. Sin. 6(2): 222, 1957) is treated as a member of the Piperaceae (= Zippelia Blume, see Y.Q.Cheng et al., Fl. China 4: 110, 1999). G.F.Buddell & J.W.Thieret, <strong>Saururaceae</strong>, Fl. N. America N. Mexico 3, Magnoliophyta: Magnoliidae and Hamamelidae, 37–38 (1997); Y.C.Tseng, <strong>Saururaceae</strong>, in Y.C.Tseng (ed.), Fl. Reipubl. Popularis Sin. 20(1): 4–11 (1982); S.C.Tucker et al., Utility of onto-genetic and conventional characters in determining phylogenetic relationships of <strong>Saururaceae</strong> and Piperaceae (Piperales), Syst. Bot. 18: 614–641 (1993); C.E.Wood, Jr., The <strong>Saururaceae</strong> in the southeastern United States, J. Arnold Arbor. 52: 479–485 (1971); N.H.Xia & A.R.Brach, <strong>Saururaceae</strong>, in Z.Y.Wu & P.H.Raven (eds.), Fl. China 4: 108–109 (1999). KEY TO GENERA 1 Herbs prostrate, ±stoloniferous; stamens shorter than styles 2. GYMNOTHECA 1: Herbs erect or ascending, rhizomatous; stamens longer than styles 2 Inflorescence a raceme, without involucral petal-like bracts; flowers with elongate flower-bract stalk (“pedicel”); fruit a schizocarp 1. SAURURUS 2: Inflorescence a dense spike, with 4 or more involucral petal-like bracts at base; flowers sessile; fruit a capsule 3 Basal leaves present; basal lamina elliptic-oblong; cauline leaves dimorphic; stamens 6 (–8); inflorescence with 4–9 involucral bracts at base (North America) 3. ANEMOPSIS 3: Basal leaves absent; cauline lamina broadly ovate or ovate-cordate; stamens 3, rarely 4; inflorescence with 4 (rarely 6 or 8) involucral bracts at base (Asia) 4. HOUTTUYNIA 1
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