The Identity of Amaranthus caturus Heyne

Abstract

To my knowledge, Heyne never published a formal description of Amaranthus caturus. The main evidence of the association of his name with the taxon is presumably the label on the sheet No. 6900 in the Wallich Herbarium (K-W) at the Royal Botanic Gardens, Kew, on which is a specimen (P1. 4, p. 64) collected from somewhere in south India (Deccan Peninsula). The label written by Heyne reads: 'Amaranth. sp. n. Caturus mihi. Spicis lateralib. terminalibusque'. It appears, as Mr. J. P. M. Brenan kindly informs me, that the binomial became current from the label on various duplicates of Wallich Herb. No. 6900 distributed to other herbaria in Europe and elsewhere and also from the mention of the name in the unpublished Wallich Catalogue itself. Hooker (1885) adopted the name and gave a detailed description of the said specimen; therefore the authority should be corrected to read 'A. caturus Heyne ex Hook. f.', if the binomial has to stay. However, the issue at present is not only of nomenclature but also of the taxonomic status of the taxon; the latter, of course, being more important even from the nomenclatural point of view. My attention was drawn to this taxon when I found some of my collections of Amaranths in Patna had acquired labels bearing the name A. caturus Heyne originating from the Central National Herbarium, Calcutta (CAL). This plant has not been mentioned by Haines (1926) as occurring in Bihar and Orissa and, so far as my information goes, it is not recorded in any Flora, Indian or otherwise, except in Hooker (1885) and Gamble (1925). All of my specimens, without exception, were partially sterile with varying degrees of seed set and irregular pollen grains. That they were of hybrid origin had further been confirmed by meiotic anomalies observed in the dividing pollen mother cells, the details of which are beyond the scope of this paper. On investigation it was found that Gamble had not seen the specimen No. 6900 in the Wallich Herbarium named Amaranthus caturus when he wrote his Flora. But he had seen another important specimen, namely the duplicate of it at Edinburgh (E), which is mounted on a sheet with another gathering and had been received from Herb. Wight via Glasgow University. This specimen has a similar annotation in Heyne's handwriting, and Gamble had added a note stating that the gathering was missing from the Wallich Collection at Kew. A fragment of this specimen placed in the Kew Herbarium (K) by Gamble bears the following inscription signed by Gamble on Ist May 1924: 'No. 6900 is missing from the Wallich Colln.-but Heyne's own original specimen is in the Herbarium at Edinburgh, written up by himself'. On the same sheet as the fragment at Kew is a rough sketch of the Wallich Herbarium specimen of Heyne's gathering and a note regarding a photograph of the Edinburgh sheet signed by S. T. Dunn, and dated 2nd July 1924. How Gamble failed to find the specimen in the Wallich