703. INDIGOFERA HOWELLII Brian Schrire, Susyn Andrews and ...

Potanin s.n. (LE!, K!) was collected in western Gansu in 1885. More
recently, this specimen and thus the species has been redetermined by
BS as I. szechuensis Craib, a species introduced by Roy Lancaster into
cultivation in the United Kingdom under Lancaster 959 in the early
1980s. Therefore I. potaninii Craib must be regarded as a synonym of
I. szechuensis. In horticulture, the name I. potaninii refers to a number
of different Indigofera species and it should be abandoned. The recent
account of Indigofera in the Flora of China (Xinfen & Schrire, 2010) has
incorrect distribution and habitat notes (see correct distribution on
page 90).
No mention was made of Indigofera potaninii by W.J. Bean (1914),
then the Assistant Curator at the Royal Botanic Gardens, Kew.
Bean (1933, 1973) did however refer to material collected by
William Purdom in Gansu, Purdom 539a, which should now be
called I. amblyantha Craib.
A collection, Farrer 260 from Gansu in 1914–1915, was identified
as I. potaninii (Bean, 1973). Seed was sent to Sir Frederick Stern’s
chalk garden at Highdown, near Worthing in Sussex, where it was
grown on and sent to Kew in 1921 for identification (K!). Another
of his collections was Farrer 1241, from Upper Burma (now northeast
Myanmar) in 1919. Plants of this were grown at Gunnersbury
House, Acton, Middlesex, one of four properties owned by Leopold
de Rothschild (1845–1917). Herbarium material from this collection
came to Kew in August 1921, J.H. s.n. (K!), where it was identified as
‘Indigofera sp. very near I. potaninii (not matched)’. Both these Farrer
numbers appear to be I. pendula, which is closely related to I. howellii.
However, I. pendula occurs in north-west and west Yunnan as well
as south-west Sichuan. To date, we have been unable to locate the
original herbarium specimens of the two Reginald Farrer collections
mentioned above and remain puzzled by the out-of-range localities
of Myanmar and Gansu. The only area to our knowledge where the
two species overlap is around Zhongdian, Yunnan (see page 82).
The first time that Indigofera potaninii appeared in one of Hilliers’
nursery catalogues was in No. 32 that was produced in 1921–1922
(John Hillier, pers. comm.). It mentioned that this was a new species
and cost 3/6 per plant (Anon, 1921). It was not until Catalogue No.
38T (1928–1929) was published that a description was given:
74 © The Board of Trustees of the Royal Botanic Gardens, Kew 2011.