6. Hypericum hypericoides (L.) Crantz (St. Andrew’s cross)

Ascyrum hypericoides L.

Pl. 361 i, j; Map 1566

Plants shrubs to 10–80(–150) cm tall. Stems spreading or ascending. Bark reddish brown, smooth, peeling in thin strips or flakes. Twigs angled or ridged below each leaf, reddish brown, the older stems usually angled below each leaf. Leaves obscurely jointed just above the base (the bases frequently persistent after the leaves have been shed), more or less evergreen. Leaf blades 5–35 mm long, 2–8 mm wide, oblanceolate to narrowly oblong or linear, rounded to bluntly pointed at the tip, tapered or narrowed at the base (sometimes with a pair of minute, rounded lobes at the jointed base), the margins often slightly rolled under at maturity, herbaceous to somewhat leathery in texture, with 1 main vein visible (sometimes difficult to observe), the surfaces with minute resinous dots, these yellowish brown to dark green or nearly black, the upper surface green, the undersurface slightly paler, not glaucous. Inflorescences usually of solitary flowers at the branch tips and upper leaf axils, occasionally with small clusters of 3 flowers at the branch tips. Flowers somewhat zygomorphic. Sepals 2 or 4, usually with minute, yellowish brown to dark green or black resinous dots, the outer pair 5.0–12.5 mm long, becoming somewhat enlarged at fruiting, broadly ovate to narrowly elliptic, rounded to shallowly cordate at the base; the inner pair absent or 1–4 mm long, lanceolate to narrowly lanceolate. Petals 4, grouped into 2 pairs, 6–11 mm long, narrowly oblong-elliptic to narrowly obovate or less commonly obovate, pale yellow to lemon yellow, shed before fruiting. Stamens 35–50, the filaments not fused into groups. Ovary from 2 carpels but 1-locular, the placentation parietal. Styles 2, free above the base, somewhat spreading or curved outward, the stigmas minute. Fruits 5–9 mm long, elliptic-ovoid to oblong-elliptic-ovoid, widest at or slightly below the midpoint, tapered abruptly to the short beaks, flattened and thus narrowly elliptic in cross-section. Seeds numerous, 0.6–0.8 mm long, the surface with fine longitudinal lines, these sometimes forming a faint network, dark brown to purplish brown. 2n=18. July–October.

Scattered in the Ozark, Ozark Border, Glaciated Plains, and Mississippi Lowlands Divisions (eastern U.S. west to Kansas and Texas; Mexico, Central America, Caribbean Islands). Bottomland forests, mesic to dry upland forests, banks of streams and rivers, and occasionally margins of ponds and lakes; also roadsides and open, disturbed areas, usually on acidic substrates.

The flowers of St. Andrew’s cross often are neither particularly abundant nor very showy, and the species is thus sometimes overlooked in the field. Steyermark (1963) noted that the species is browsed by deer. He also suggested that it makes a desirable cultivated plant, particularly in rock gardens, but the species apparently is not winter-hardy in the northern half of the state.

Hypericum hypericoides and four or five closely related species sometimes have been segregated into the genus Ascyrum L. (Steyermark, 1963; Kaul, 1986), based primarily on their flowers with two pairs of unequal sepals and the four petals strongly spreading and grouped into two pairs. Most botanists currently believe that this group is best treated as a section or subsection within the classification of the large and morphologically diverse Hypericum (Adams and Robson, 1961; Robson, 1996). Circumscription of the H. hypericoides complex also has been controversial. The two morphological entities in Missouri are relatively easily distinguished and tend to maintain their leaf shape and growth-form characteristics, even when growing side by side. They have been treated variously as separate varieties (Adams, 1959; Steyermark, 1963; Cooperrider, 1989), subspecies (Robson, 1980, 1996), or species (Adams and Robson, 1961; Adams, 1962; Wood and Adams, 1976; Gleason and Cronquist, 1991). A third variant endemic to the Dominican Republic has been described as ssp. prostratum N. Robson and differs in details of its strongly prostrate stems, stem-branching pattern, and generally smaller leaves. Because the Caribbean taxon has only been described at the subspecies level, the present treatment of the complex follows the most recent taxonomic revision of the group (Robson, 1996) in recognizing the Missouri taxa as subspecies.