CAPRIFOLIACEAE (Honeysuckle Family)
Contributed by
Alan Whittemore
Plants shrubs,
small trees, lianas, or perennial herbs. Leaves opposite, simple or pinnately
compound but infrequently lobed. Stipules absent or, if present, relatively
inconspicuous and scalelike or glandular. Inflorescences consisting of
solitary, paired, or densely clustered flowers in the leaf axils or of terminal
clusters or panicles. Flowers perfect (in paniculate species, occasionally some
of the marginal flowers sterile), epigynous. Calyces 5-lobed, actinomorphic,
fused to the ovary, the tube sometimes extending slightly past the ovary,
usually persistent at fruiting. Corollas 5-lobed, actinomorphic and funnelform
to cup-shaped, bell-shaped, or saucer-shaped, or strongly zygomorphic and
strongly 2-lipped, white, cream-colored, yellow, pink, or red. Stamens 5, the
filaments distinct, attached to the base of the corolla. Anthers oblong to
oblong-elliptic or nearly linear, attached above the base on the dorsal side.
Pistil 1 per flower (but the ovaries of adjacent flowers sometimes fused), of 2–5
fused carpels. Ovary inferior, with 2–5 locules, the placentation axile. Style
1 per flower with the stigma capitate and sometimes shallowly 2–5-lobed or
absent and the sessile stigma deeply 3–5-lobed (usually appearing as 3–5
separate stigmas). Ovules 1 to numerous per locule. Fruits berries or berrylike
drupes with one to several seeds or seedlike stones. Fifteen genera, about 400
species, nearly worldwide, most diverse in temperate and montane regions.
Many species of
Caprifoliaceae are popularly cultivated as ornamentals. In addition to the
genera treated here, two groups of mostly Asian bush honeysuckles, Abelia
R. Br. and Weigelia Schreb., are commonly seen in gardens. They differ
from the genera present in the wild in Missouri by their sepals, which are
large and prominent, and their fruits, which are dry and capsular.
The
circumscription of Caprifoliaceae in the present treatment is the traditional
one (Steyermark, 1963; Cronquist, 1981, 1991). However, phylogenetic studies in
recent years have suggested that a broad renovation of familial limits in the
order Dipsacales is necessary (Donoghue et al., 1992, 2001; Judd et al., 1994;
Bell et al., 2001). Both morphological and molecular data provide evidence that
the broad traditional circumscription of Caprifoliaceae does not accurately
reflect the phylogeny of the group, because the core of the family (including
the Missouri genera Lonicera, Symphoricarpos, and Triosteum) is
more closely related to members of the Dipsacaceae and Valerianaceae than to
other genera traditionally included in the family. The two Missouri genera with
sessile stigmas and saucer- or cup-shaped corollas, Sambucus and Viburnum,
along with three small herbaceous genera, Adoxa L., Sinadoxa C.Y.
Wu, Z.L. Wu & R.F. Huang, and Tetradoxa C.Y. Wu, probably are better
treated in a separate family, Adoxaceae. Some authors have gone so far as to
submerge Dipsacaceae and Valerianaceae into a redefined Caprifoliaceae (Judd et
al., 2002), but further details of familial limits within the order remain to
be elucidated through broader taxon sampling and more detailed studies within
the major branches of the overall phylogenetic tree.