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.