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.