OLEMONIACEAE (Phlox Family) Contributed by Carolyn J. Ferguson

Plants annual, biennial, or perennial herbs (woody elsewhere). Stems unbranched or more commonly branched, glabrous or hairy and/or glandular, the hairs lacking persistent pustular bases. Leaves alternate or opposite and sometimes also basal, well-developed, sessile or petiolate. Stipules absent. Leaf blades simple or pinnately deeply divided to compound, the surfaces usually hairy (sometimes becoming glabrous or nearly so at maturity), the hairs lacking persistent pustular bases and not roughened to the touch. Inflorescences terminal and/or axillary, of solitary flowers or clusters, these sometimes grouped into panicles, not appearing paired or coiled, the individual flowers often not subtended by bracts (but the branch points sometimes with bracts). Flowers actinomorphic (somewhat zygomorphic elsewhere), hypogynous, perfect; cleistogamous flowers absent. Calyces usually 5-lobed, often with thicker green lobes extending the length of the tube and intervening thin, translucent areas (these delicate and often rupturing as the fruits mature), usually not becoming enlarged at fruiting, the lobes equal, more or less persistent at fruiting. Corollas usually 5-lobed, usually spirally twisted in bud, trumpet-shaped or bell-shaped. Stamens usually 5, the filaments attached in the corolla tube, not subtended by scales, usually relatively short, but occasionally somewhat unequal in length, the anthers not exserted or some or all of them somewhat exserted, appearing 2-locular, usually attached near the dorsal midpoint, white, red, dark purple, or blue. Pistil 1 per flower, of usually 3 fused carpels. Ovary unlobed to bluntly 3-angled or 3- or 6-ribbed, 3-locular, with 1–10 ovules per locule, the placentation axile. Style 1, attached at the tip of the ovary, usually 3-branched at the tip, persistent or not at fruiting, the branches stigmatic on the inner surface for most of their length, slender. Fruits capsules, dehiscent longitudinally (sometimes tardily or incompletely so), usually with 3 valves, with 1–12 seeds per locule. About 26 genera, about 375 species, most diverse in the New World, but also in Europe, Asia.

Economic importance of the Polemoniaceae is chiefly horticultural, with numerous cultivated ornamentals in the family (particularly within Phlox, Ipomopsis, Polemonium). The family has received much attention from evolutionary biologists over the decades, and is of particular interest due to diversification in varied ecological habitats of western North America, its center of diversity (e.g., V. Grant 1959; V. Grant and K. Grant, 1965). The family is taxonomically complex, and generic delimitation has been unstable through history. Recent, extensive phylogenetic work for the family and its constituent genera has advanced our understanding of diversity in the group (see L. A. Johnson et al., 2008), and a phylogenetic classification of three subfamilies and 26 genera has emerged (J. M. Porter and Johnson, 2000). Most of these genera, including all members of the Missouri flora, are grouped within a large temperate subfamily Polemonioideae, with the remaining genera in the tropical subfamily Cobaeoideae Arn. and the monotypic subfamily Acanthogilioideae J.M. Porter & L.A. Johnson (Baja California, Mexico). Continued study of the family hopefully will clarify relationships of the genera. The systematics of particular genera remains complicated, presenting challenges relating to hybridization, polyploidy, presence of cryptic species, etc. Ongoing work within genera can be expected to further highlight diversification and species boundaries within this interesting family. Wilken (1986) is noted as a reference for information on the non-Phlox taxa.