Monographs Details: Borreria densiflora DC.
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Scientific Name:Borreria densiflora DC.

Spermacoce spinosa L., Sp. Pl. ed. 2. 148. 1762, as to name, but not as to plant.

Spermacoce spinosa Sw., Obs. Bot. 45. 1791, not Jacq. 1760, nomen, nor Jacq. 1763, nor L. 1762.

Borreria spinosa (L.) Cham. & Schl., Linnaea 3: 340. 1828.

Both de Candolle and Swartz described this taxon from Jamaican material. Borreria densiflora DC. is the earliest legitimate name for the species now passing as B. spinosa. I am indebted to Dr. J. P. M. Brenan and Mrs. S. Phillips of the herbarium of the Royal Botanic Gardens, Kew, for information regarding the typification of B. spinosa. Jacquin’s Spermacoce spinosa published in 1760 (Enum. Syst. PI. 12) is a nomen nudum, while his publication under that name in 1763 (Sel. Stirp. Am. 21), based on a collection from Havana, Cuba, pertains to plants with 4-lobed calyx, ovate calyx lobes, internally pilose corolla exceeding the calyx, obovate petiolate leaves, and in habit a woody shrub with subulate spines-obviously characters all at variance with the plants passing as Borreria spinosa. Linnaeus (Sp. Pl. ed. 2. 1: 148. 1762) referred to both Jacquin’s Spermacoce spinosa and to Loefling’s Spermacoce suffruticosum (Pl. Amer. 201. 1758), and Linnaeus’s description does not fit the plant now passing as Borreria spinosa, since the taxon Linnaeus described has few-flowered verticils of flowers, stems “ad basin ramosi” and “diffusi, duri,” whereas the plants now passing as Borreria spinosa have many-flowered heads, and solitary, herbaceous, erect, usually unbranched, rarely branched stems. Loefling’s description of Spermacoce suffruticosum refers to a suffruticose plant with perennial roots, oblong leaves, and only three to four sessile flowers.

Since Linnaeus cites the name Spermacoce suffruticosum Loefl., which had been previously validly published, as a synonym of Spermacoce spinosa, the latter name is superfluous and must therefore be rejected. The taxon described by Linnaeus must be judged as based on a specimen collected by Loefling and described by that author as Spermacoce suffruticosum. In the Linnaean Herbarium specimen no. 125.0, labelled Spermacoce spinosa, collected by Rolander, does not agree with the plant now passing as Borreria spinosa nor with Linnaeus’s description. On the other hand, specimen on the left hand side of no. 125.1 in the Linnaean Herbarium matches the plant now passing as Borreria spinosa with respect to such characters as the glabrity and size of stem, size of heads, leaf shape and size, and prominent midrib of leaves, but it does not match Linnaeus’s description, and is labelled Spermacoce tenuior. This latter specimen (left hand side of 125.1) could have come to Linnaeus later than 1762, and there is no concrete evidence that it can be linked with Linnaeus’s Spermacoce spinosa. Since, moreover the specimen of 125.1 on the left hand side of that sheet in the Linnaean Herbarium does not agree with the description, the best alternative appears to be that of rejecting Spermacoce spinosa as an ambiguous name and to take up the name Borreria densiflora DC. as the earliest legitimate name for what is now passing as B. spinosa.