The Central American plants previously known as Aristolochia thwaitesii Hooker are described as new and given the name Aristolochia stevensii Barringer. The name A. thwaitesii is correctly used for a Chinese species. Two different species have come to be called Aristolochia thwaitesii Hooker. One is native to Central America (Pfeifer, 1966) and one is native to China (Hwang, 1988; Ma, 1989). W. D. K. Thwaites was an energetic collector and director of the Botanical Garden at Perideniya, Ceylon [Sri Lanka]. He collected in Ceylon and Great Britain, so how a Central American and a Chinese species came to be named for him is a puzzle. William Hooker (1856) illustrated and described Aristolochia thwaitesii from a cultivated specimen growing at Kew. The plant was an unusual suffruticose herb with narrowly ovate leaves and basal, branching inflorescences. The flowers had curved calyces and a three-lobed gynostemium. He believed that the original seed was received from Ceylon and named the species in honor of Thwaites. Later, in a note after a plate of the Central American species A. arborea Linden, Hooker (1862) noted that A. thwaitesii was not from Ceylon and guessed that it might be similar to a species collected by Purdie in Santa Marta, Colombia. Following up on this reference, Pfeifer searched the New World material for a plant resembling the original description and illustration. In Central America, the shrubby, cauliflorous species with threelobed gynostemia form a distinctive group that includes Aristolochia arborea and A. panamensis Standley. Pfeifer (1966) discovered specimens that appeared to match the original description and assigned them to A. thwaitesii. He did not realize that the true A. thwaitesii had been located elsewhere. Ten years after his father's note, J. D. Hooker (1871) had published a further note after a plate of Dorstenia mannii Hooker f. that went unnoticed by Pfeifer. Hooker wrote that Aristolochia thwaitesii was not from either Ceylon or Colombia but from the Old Calabar River region of east Africa, what is now southern Nigeria. He had received a note from Mr. Bullen, a curator at Glasgow, that a specimen matching the description had been sent by Mr. Thompson from that area. This, too, would prove to be mistaken. Later, Tuchter (1905) collected a plant that matched Hooker's original description and plate. He found it growing under bamboo near Wong Ne Chong and at the base of Black Mountain on Hong Kong. These plants are the true Aristolochia thwaitesii and have been described as such by Tuchter (1905), Dunn & Tuchter (1912), Hwang (1988), and Ma (1989). They match the protologue and the lectotype, Westland s.n. (K). The Purdie collection W. J. Hooker saw and confused with Aristolochia thwaitesii is probably A. maxima Jacquin. That species is a woody liana with 6-lobed gynostemium that often has narrowly ovate to lanceolate leaves and branched, basal inflorescences. It is common around Santa Marta (Gonzalez, 1990), and a Purdie collection exists that has very long inflorescences. The African plant grown at Glasgow from Old Calabar is probably A. (Pararistolochia) juju S. Moore, a liana with a triangulate calyx limb and cauliflorous, racemose inflor cences. A collection by Mann from Old Calabar exists. The Central American species, called A. thwaitesii by Pfeifer (1966), is a distinct species now in need of a name. Aristolochia stevensii Barringer, sp. nov. TYPE: Nicaragua. Matagalpa: along Hwy. 3, 6.6 km N of Matagalpa (El Tuma intersection), ca. km 137.5, 12?59'N, 85?55'W, 1,200-1,250 m, 24 May 1981, Stevens & Henrich 20353 (holotype, BKL; isotypes, F, MO). Figure 1. Species A. rhizanthae Lundell affinis sed liana foliis ovatis cordatis seu auriculatis subtis tomentosis utriculis truncatis differt; ab A. thwaitesii Hooker limbo calycis manifeste tridentato gynostemii columna differt. Liana. Stems woody, to 2 cm diam., the young stems tomentose, the older stems with slightly winged, corky bark. Pseudostipules absent. Leaves alternate; pe ioles 10-15 mm long, 2-3 mm diam., tomentose; blades ovate, 9-17 cm long, 4-9 cm wide, subcoriaceous, glabrous above, tomentose below, the base cordate-auriculate, the lobes 10-12 cm long, often NOVON 3: 321-323. 1993. This content downloaded from 207.46.13.124 on Sun, 11 Sep 2016 05:43:58 UTC All use subject to http://about.jstor.org/terms