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Re-evaluation of generic characters for Blinkworthia (Convolvulaceae) based on morphology and reproductive organ development

Rattanakrajang, Pantamith, Traiperm, Paweena, Staples, GeorgeW.
Plant systematics and evolution 2018 v.304 no.3 pp. 415-429
Argyreia, bracts, flowers, ontogeny, shrubs, small fruits
Blinkworthia, a tropical Asian genus of Convolvulaceae, was first characterized as an erect shrub with solitary flowers, three involucral bracts, and indehiscent, one-seeded berries. These three characters are diagnostic traits long used to distinguish Blinkworthia from other genera in the family. Blinkworthia lycioides was selected as a representative species for investigation of both morphology and ontogeny of the reproductive parts, while B. convolvuloides was only investigated morphologically. Nine stages based upon floral and fruit sizes were collected and prepared by the paraffin method for the developmental study. Examination of the developmental anatomy proved that some of the morphological characters have been misunderstood. In fact, none of the generic characters historically used to define the genus Blinkworthia are unique: the same character states are present in some species of Argyreia. This highlights that on morphological grounds it is not tenable to maintain Blinkworthia distinct from Argyreia. Pending the results from our ongoing molecular study of the genera in tribe Ipomoeeae a firm decision can be taken regarding the generic circumscription.