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SPERMACOCE L. [family RUBIACEAE]

Herbarium
Royal Botanic Gardens, Kew (K)
Collection
Flora of Tropical East Africa
Resource Type
Reference Sources
Entry From
Flora of Tropical East Africa, page 1, (1976) Author: B. VERDCOURT
Names
SPERMACOCE L. [family RUBIACEAE], Sp. Pl.: 102 (1753) & Gen. Pl., ed. 5: 44 (1754)
Borreria G. F. W. Mey. [family RUBIACEAE], Prim. Fl. Esseq.: 79, t. 1 (1818)
Octodon Schumach. & Thonn. [family RUBIACEAE], Beskr. Guin. Pl.: 74 (1827)
Hypodematium A. Rich. [family ], Tent. Fl. Abyss. 1: 348 (1848), non Kunze (1833)
Dichrospermum Bremek. [family RUBIACEAE], in B.J.B.B. 22: 75 (1952)
Arbulocarpus Tennant [family RUBIACEAE], in K.B. 12: 386 (1958)
Information
Annual or perennial herbs or small subshrubs, with glabrous, pubescent, hispid or scabrid very often 4-angled prostrate to erect stems. Leaves opposite or falsely whorled, sessile or petiolate, the petioles often united with the stipule-sheath, which is mostly divided into 1-many ± filiform fimbriae. Flowers mostly small or occasionally medium-sized, hermaphrodite, not heterostylous (except in sect. Galianthe (Griseb.) K. Schum. which does not occur in Africa), sessile, mostly in axillary ± globose often very many-flowered clusters or less often in terminal capitula, supported by 1–2(-more) pairs of leaves forming bracts, or 1-few in the axils (some extra-African species have extensive terminal inflorescences); sometimes the axillary nodal clusters run together to form a spike-like inflorescence the leaf pairs forming scattered or congested bracts; the flowers in the globose clusters are frequently intermixed with numerous ± scarious filiform bracteoles. Calyx-tube obovoid, turbinate or obconic; lobes 2–4(–8), mostly triangular, oblong or lanceolate, often ± persistent, sometimes with intermediate denticles. Corolla funnel-shaped or salver-shaped, the tube sometimes very slender; throat glabrous to hairy; lobes (3–)4, mostly spreading, valvate. Stamens 4, the filaments inserted in the tube or at the throat, the linear to oblong anthers included or mostly exserted. Ovary 2-locular, the amphitropous ovules solitary in each locule, attached to the middle of the septum; style filiform, mostly exserted; stigma capitellate or with 2 short lobes. Fruit mostly a 2-valved capsule dehiscing from the apex downwards with the septum disappearing (in sect. Borreria (G. F. W. Mey.) Verdc.) or sometimes 2-coccous, one dehiscent but the other remaining ± closed (sect. Spermacoce) or in a few species (sect. Arbulocarpus (Tennant) Verdc.) the capsule splitting from the base upwards but valves remaining attached by the calyx-limb which is not split across, the whole falling off like a lid, a persistent septum being left behind. Seeds oblong, ellipsoid or ovoid, usually shining brown with a thin often clearly reticulate testa, ventrally grooved; albumen horny or fleshy.
Range
A large genus of worldwide distribution in the tropics and subtropics, with some 150–250 species according to various estimates, mainly American but with many species in Africa and some also in most tropical and subtropical areas; many have become weeds of cultivation.
Notes
Some of the species are very similar in facies to members of the Oldenlandia group of genera but can always be absolutely distinguished by the solitary ovules and discoid pluricolpate pollen grains.It has been accepted practice for a hundred years or so to split up this genus, but although the technical characters of the fruit dehiscence sound admirable on paper there is no associated habit facies and it is not possible without additional knowledge to assign flowering material to the genera concerned. I have therefore followed Hooker in G.P. 2: 145 (1873) in his circumscription of the genus with the addition of Octodon (which he kept separate) to the synomymy as suggested by Hepper (K.B. 14: 260 (1960)). Bremekamp (Rec. Trav. Bot. Néerland. 31: 305 (1934)) who has been responsible for much generic segregation in this family states his position as follows. “The differences between Diodia, Spermacoce and Borreria are also very small and hardly of sufficient importance to justify their separation. In contradistinction with the difference between Diodia and Hemidiodia which is not only taxonomically of little value but also difficult to see the differences between Diodia, Spermacoce and Borreria are at least easily recognizable. For this admittedly purely opportunistic reason I have retained these genera.” I agree entirely but I must report that Steyermark (in litt.), although agreeing with much of this argument, thinks the technical characters are adequate and maintains the genera, thus avoiding a great many name changes since very many S. American species have been described in Borreria. As far as the African species are concerned I would also unite Spermacoce with Diodia and the very close relationship can be seen by comparing Diodia sarmentosa with Spermacoce princeae, but a survey of the New World material of Diodia has convinced me this would not be a wise course—certainly the type species of Diodia, D. virginiana L. differs widely in its fruit structure.I have found no satisfactory logical way to arrange the species, in fact this will be impossible until a thorough revision is made on a world basis. K. Schumann’s classification of Borreria (E. & P. Pf. IV.4: 143 (1891)) as follows, is of no value for arranging the African species.Sect. BorreriaSeries Tenellae K. Schum.Subseries Virides K. Schum. (including Octodon)–S. laevis, S. ocimoides, S. pusilla and S. dibrachiata belong hereSubseries Glaucae K. Schum.Subseries Radiatae K. Schum.—S. radiata and S. chaetocephala belong hereSeries Latifoliae K. Schum. S. latifolia belongs hereSect. Trachiphyllum K. Schum.Sect. Galianthe (Griseb.) K. Schum.
SPERMACOCE L. [family RUBIACEAE]
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