41. Kelloggia Torrey ex Bentham & J. D. Hooker, Gen. Pl. 2: 137. 1873.
钩毛草属 gou mao cao shu
Authors: Tao Chen & Friedrich Ehrendorfer
Herbs, perennial, sometimes slightly woody at base; rootstock slender, with short rhizomatous and somewhat woody branches and with ascending or erect stems. Raphides present. Leaves opposite, decussate, subsessile, without domatia; stipules persistent, interpetiolar, hardly fused to petioles, triangular to linear or ± irregularly divided and often mutifid to fimbriate. Inflorescences thyrsoid, with terminal and axillary branches at uppermost nodes, pedunculate cymes often with umbelliform flower groups, not rarely with new axes developing and older axes elongating making inflorescences expansive, lax, few to many flowered and bracteate; uppermost bracts often reduced to multifid or fimbriate stipules. Flowers pedicellate, bisexual, monomorphic. Calyx teeth 4 or 5, narrowly lanceolate, hardly fused at base. Corolla white to pink or red, funnelform, divided to ca. 1/2 into 4 or 5 lobes, glabrous inside and valvate in bud. Stamens 4 or 5, inserted in corolla throat, finally slightly exserted; filaments flattened; anthers dorsifixed near base. Ovary inferior, densely covered with hooked trichomes, 2-celled, ovules 1 in each cell, erect, basal; style with 2 short, linear stigmas, exserted. Fruit with calyx teeth ± persistent, schizocarpous, dividing into 2 oblong to ellipsoid, leathery and indehiscent mericarps, densely covered with hooked trichomes; each mericarp with 1 medium-sized, ellipsoid and plano-convex seed; endosperm fleshy; embryo large; cotyledons leaflike; radicle hypogeous.
Two species: disjunct, one in China and Bhutan, the other in W North America (Mexico, United States); one species in China.
In general aspect, Kelloggia resembles Galium, particularly with respect to the inferior ovary (hypanthium) developing into dry schizocarps covered with hooked trichomes. Presumably, these fruit disperse similarly to those of Galium as "stick-tights," by attaching to animals. In contrast to Galium and other Rubiinae, Kelloggia has 3-colpate (and not polycolpate) pollen grains, calyx teeth, and not leaflike interpetiolar stipules, making sterile plants resemble Nertera and Neanotis. In spite of these differences, Robbrecht and Manen (Syst. & Geogr. Pl. 76: 85-146. 2006) have transferred Kelloggia from the tribe Paederieae to the tribe Rubieae as a monotypic and basal subtribe Kelloggiinae. We concur with this transfer but not with the inclusion of the totally different Theligonum into the Rubieae, which should be left in a separate tribe, Theligoneae (see also Bremer & Eriksson, Int. J. Pl. Sci. 170: 766-793. 2009). Kelloggia and all other Chinese Rubieae taxa have been briefly discussed and keyed out under Galium in the present volume.
All generic descriptions of Kelloggia give the number of calyx and corolla lobes as "4 or 5," implying that both conditions are equally common as apparently is the case in the North American species. However, all the Asian specimens studied have 5 calyx and corolla lobes, as shown in the FRPS illustration (71(2): 157, t. 41. 1999) and described by Springate et al. (Fl. Bhutan 2(2): 822. 1999).
The morphology, circumscription, biogeography, and molecular phylogeny of Kelloggia were studied by Nie et al. (Amer. J. Bot. 92: 642-452. 2005). They concluded that the two species of the genus are most closely related to each other, that Kelloggia arrived in North America through long-distance dispersal from Asia, and that it occupies a basal position within Rubieae.