NEW SPECIES, NEW COMBINATIONS, AND NEW RECORDS IN CONVOLVULACEAE FOR THE FLORA OF THAILAND
corrected determinations, will be made available on-line via the BRAHMS Projects website (http://herbaria.plants.ox.ac.uk/bol/databases/default.aspx) when the full account of the family is published in the Flora of Thailand.
C. The Argyreia confusa situation
There is a considerable confusion among several named species of Argyreia from the Indian subcontinent, involving plants called A. thomsonii (C.B.Clarke) Babu or A. nasirii D.F.Austin, A. setosa (Roxb.) Choisy or A. strigosa (Roth) Roberty, A. hirsutissima (C.B.Clarke) Raizada, A. peguensis Ridl., A. capitata (Vahl) Choisy, and probably others, as well as numerous infraspecific taxa. In the Flora of China (Fang & Staples 1995) I (GS) speculated that Ipomoea hirtifolia R.C.Fang & S.H.Huang was actually an Argyreia and I now believe this Tibetan plant is part of this same species complex. Whatever name is applied to them, the plants have a distinctive facies: herbaceous climbers with all parts more or less appressed-setose; ovate leaves 2.5–9 cm long with cordate bases; axillary inflorescences on peduncles shorter than the subtending petioles, cymosely 1–3-flowered; bracts 2 or 3, oblong to spatulate, persistent; pedicels 0–3 mm long; corollas tubular to narrowly funnelform, deep purple-red (or white?); corolla setose outside on the midpetaline bands. A full description of the Thai plants will be provided in the flora account; the foregoing diagnostic characters will permit recognition of the plants anywhere they occur; in particular the persistent bracts a top the rather short peduncle and (sub)sessile flowers/ fruits are immediately recognizable. One member of this complex reaches the edge of its range in northern Thailand and a few specimens of it have been seen, scattered in various herbaria.
Several botanists who published on Indian Convolvulaceae (Roxburgh 1824; Wallich 1832; Choisy 1834; Clarke 1883) tried to rationalize and stabilize the use of names in this complex, without much success. Mostly they seem to have misunderstood the species delimitation and further confused the situation by frequent misapplication of names. Prain (1894: 92–96) attempted to rationalise this muddle of misapplications and superfluous names, while providing names for three species of this complex that range into Burma. However, his explanation of the taxonomic ideas of his predecessors, and their nomenclatural consequences, makes little sense without access to type material for all the names involved. Unfortunately these types are widely scattered, where they are known to exist at all, and several are conserved in herbaria that do not loan historic specimens, making a full resolution of this situation impractical at this time. For purely utilitarian reasons—the need for a name that can be used for the Thai plants—we have followed Kerr (1954) in the choice of epithet for plants found in northern Thailand, Myanmar, and also southwestern China. Only a careful revision that takes into account all the type material will be able to sort out how many species there are and what is the correct name for each. To our eyes there may be only a single variable species that has been named many times based on slight morphological variants (primarily indumentum density, color, and type, which have proven to be unreliable characters) and geopolitical considerations. When such a study is completed the name A. confusa (Prain) Raizada will surely be displaced by one of the older epithets; for now we are taking it up for the Thai flora.