13. Galium triflorum Michx. (fragrant bedstraw)
G. triflorum var. asprelliforme Fernald
Pl. 548 c, d;
Map 2547
Plants
perennial. Stems 20–70 cm long, spreading to loosely ascending, weak and often
trailing, clambering on other vegetation, and/or matted, usually well-branched,
sometimes only near the base, glabrous or sparsely to moderately pubescent with
short, spreading to downward-angled hairs on the angles. Leaves (4)5 or 6 per
node, more or less spreading in orientation. Leaf blades 5–35(–45) mm long,
2–10(–15) mm wide, narrowly elliptic to elliptic or oblanceolate, the smallest
occasionally linear or ovate, rounded or angled to a bluntly pointed tip, the
midvein extended into a short, sharp point, angled or tapered at the base, the
undersurface not glandular, glabrous or sparsely roughened with minute,
downward-angled, pricklelike hairs along the midvein, the venation with only
the midvein visible, the margins roughened with minute to short, stiff,
ascending hairs, flat or slightly curled under. Inflorescences terminal and
usually also axillary from the upper leaves, not pendant, positioned over the
leaves, usually consisting of small (1–5 cm long), stalked clusters or small
panicles, with mostly 1–3 branch points. Flowers 3 to several, the stalks 1–6
mm long (becoming elongated to 10 mm at fruiting). Corollas 1.0–1.2 mm long,
4-lobed, white. Fruits 1.5–2.5 mm long, 1.5–2.5 mm wide, the surface densely
pubescent with hooked hairs ca. 0.8 mm long. 2n=44, 66. May–September.
Scattered nearly
throughout the state (U.S. [including Alaska]; Canada, Mexico, Greenland,
Europe, Asia). Bottomland forests, mesic upland forests, banks of streams,
rivers, and spring branches, margins of sinkhole ponds, fens, and ledges of
bluffs; also pastures, old quarries, railroads, and roadsides.
Galium
triflorum is sometimes
used to flavor drinks, including wine, and the flowers have a sweet aroma
reminiscent of vanilla. The epithet triflorum refers to the usual
arrangement of the flowers in clusters of three. This arrangement is quite
characteristic of G. triflorum plants to our north, and also very common
but not so consistent in Missouri plants. As with most wide-ranging species,
several varieties have been recognized within G. triflorum. Steyermark
treated our plants as var. triflorum, commenting that the other North
American variety, var. asprelliforme of the eastern United States and
adjacent Canada, is distinguished by its more numerous inflorescences with more
branching and consequently more flowers, with these accompanied by reduced
rather than full-sized leaves. With more collections of G. triflorum now
available for study, some plants from Missouri could be classified as var. asprelliforme,
whereas others are intermediate in morphology. The degree of inflorescence
development appears to be related to size and age of the plant, with most of
the compounded clusters on larger, older plants. Therefore, these varieties are
not recognized formally here.
Galium
triflorum is
superficially similar to and sometimes confused with G. aparine, but the
latter has larger fruits, narrower leaves, and is strongly roughened, whereas G.
triflorum is smooth or only slightly roughened. Voss (1996) noted that
these species can be distinguished in Michigan by the tiny spinules or barbs on
their leaf margins, which are retrorse in G. aparine but curved toward
the leaf tip in G. triflorum. Although the marginal spinules of G.
aparine are evident with careful observation under a good handlens, those
of Missouri’s G. triflorum at best are only minutely discernible with
significant magnification and sometimes spreading rather than curved.