Description from Flora of China
Adenacanthus Nees; Aechmanthera Nees; Apolepsis (Blume) Haasskarl; Baphicacanthus Bremekamp; Championella Bremekamp; Diflugossa Bremekamp; Goldfussia Nees; Gutzlaffia Hance; Hemigraphis Nees; Hymenochlaena Bremekamp; Lepidagathis sect. Apolepsis Blume; Parachampionella Bremekamp; Paragutzlaffia H. P. Tsui; Perilepta Bremekamp; Pseudaechmanthera Bremekamp; Pseudostenosiphonium Lindau; Pseudostonium Kuntze; Pteracanthus (Nees) Bremekamp; Pteroptychia Bremekamp; Pyrrothrix Bremekamp; Semnostachya Bremekamp; Sericocalyx Bremekamp; Strobilanthes subg. Pteracanthus Nees; S. subg. Sympagis Nees; Sympagis (Nees) Bremekamp; Tarphochlamys Bremekamp; Tetraglochidium Bremekamp; Tetragoga Bremekamp.
Herbs, subshrubs, shrubs, [or small trees], isophyllous or weakly to strongly anisophyllous, woody species commonly pliestesial (living for several years then dying after flowering and fruiting). Stems and branches usually 4-angled, often sulcate, basally becoming woody and hollow with age. Leaves opposite, petiolate or sessile; leaf blade adaxially usually with prominent linear cystoliths and sometimes also abaxially, margin variously dentate, serrate, crenate, undulate, or entire. Inflorescences axillary and/or terminal, bracteate heads, headlike clusters, spikes (sometimes distinctly secund), or less commonly of pedicellate flowers forming an open panicle; sterile bracts usually resembling reduced leaves and often present in compound inflorescences; floral bracts usually different from leaves, persistent or caducous as flowers open, very variable in size and shape, sometimes of two types with basal sterile bracts (outermost bracts in a capitate inflorescence) differing from inner or apical fertile ones; bracteoles 2 per pedicel, usually small, sometimes absent. Calyx usually 5-lobed to base, commonly accrescent in fruit; lobes equal or with middle one distinctly longer than others, sometimes partially fused to form a bipartite or tripartite calyx. Corolla nearly always bluish, rarely white, yellow, or pink, tubular or funnel-shaped, inside glabrous apart from trichomes retaining style except in Strobilanthes parvifolia, S. oresbia, and related species; tube either gradually widened from base or narrowly cylindric and then abruptly widened, campanulate or gibbous; limb 5-lobed; lobes usually ovate, equal or subequal, spreading, contorted in bud. Stamens usually 4 and didynamous (rarely 2, 2 fertile with 2 staminodes, or 4 fertile with a central staminode), basally monadelphous; usually 2 filaments distinctly longer than other 2; anthers included or exserted, 2-thecous; thecae oblong or subspherical, parallel, erect or incurved, glabrous, basally muticous, rarely with connective extended to a mucronate tip; pollen spherical or ellipsoid, echinulate and/or variously ribbed, usually tricolporate. Ovary oblong to obovoid, 2-locular, with 2(-8) ovules per locule; style filiform, long, slender, simple, sometimes persistent after corolla falls, retained in place by trichomes on one side of corolla tube; stigma 2-cleft with one branch longer. Capsule characteristically oblong to narrowly obovoid but sometimes fusiform to narrowly ellipsoid, (2-)4(-16)-seeded; retinacula strong, curved. Seeds usually ovate or orbicular in outline and lenticular by being flattened, usually pubescent with appressed mucilaginous trichomes which become spreading when wetted, trichomes caducous in a very few species with seed glabrescent; areola usually very small but occasionally extending as a glabrous area over much of seed surface.
Note on indumentum: in many species the young inflorescence, even when a few capsules are present, is glabrous or nearly so. As the inflorescence matures, sessile glands become stipitate and older inflorescences become gland-tipped pilose, a process parallel to the development of glands and trichomes as the ovary matures into the capsule. The calyx is also accrescent in many species and the apex appears to continue growing, so calyx lobes, which are linear-oblong at anthesis, may become subspatulate in fruit. There is also a tendency for the corolla indumentum to fall as the corolla opens. Corolla indumentum is most easily observed on buds.
Note on pollen: fig. 1 and fig. 2 show 18 pollen types found in Chinese Strobilanthes. It should be noted that the pollen of some 20% of Chinese species is unknown and the types shown here could be construed as an oversimplification. However, the images do show the range of variation found in the genus. Two important caveats should be taken into account. Many publications illustrating Strobilanthes pollen from China are marred by the use of misidentified material. This is the explanation for cases where a different pollen type is given to that in a published source. A second problem relates to the degree of infraspecific variation in pollen morphology. This is largely unstudied but it is known that some of the more widespread and variable species are somewhat diverse in their pollen morphology although all plants sampled have pollen of one general type. Species known to have somewhat variable pollen include S. atropurpurea, S. echinata, S. speciosa, and S. tomentosa.
Attempts to divide Strobilanthes (Strobilanthinae sensu Bremekamp) into segregate genera have proved unsatisfactory largely because the level of homoplasy displayed by morphological characters has to date rendered subdivision impossible. Molecular studies have not yet greatly clarified the situation because of insufficient sampling, and this too is likely to prove problematic because many species are known only from the type collection or from material inadequate for molecular study. Clusters of related species are clearly discernible, but insufficient information is currently available to produce a satisfactory infrageneric classification. Species in the following account are grouped with morphologically similar and presumably related species, but the linear sequence and lack of adequate data implies that the order of species is at least partially arbitrary.
Strobilanthes lactucifolia H. Léveillé is not treated in the present account because no material has been traced. It is probably not a species of Strobilanthes. Strobilanthes straminea W. W. Smith (Goldfussia straminea (W. W. Smith) C. Y. Wu & C. C. Hu) from N Myanmar, included in FRPS (70: 169. 2002), is excluded from the present account because no Chinese specimen can be traced. Strobilanthes deutziifolia H. Léveillé is Abelia macrotera (Graebner & Buchwald) Rehder in the Linnaeaceae (see p. 645). Strobilanthes gentiliana H. Léveillé is Sesamum indicum Linnaeus in the Pedaliaceae (see Fl. China 18: 226. 1998). Strobilanthes hypericifolia H. Léveillé is Abelia uniflora R. Brown in the Linnaeaceae (see p. 645).
About 400 species: tropical Asia; 128 species (57 endemic) in China.
(Authors: Hu Jiaqi (胡嘉琪 Hu Chia-chi), Deng Yunfei (邓云飞); John R. I. Wood)