THE PURPLE HYACINTH BEAN 
GEoRGE F. FREEMAN 
, (WITH SEVEN FIGURES) 
Students of the genus Dolichos are now somewhat perplexed 
concerning the identity of D. lignosus Linn. and D. Lablab Linn. 
According to accepted usage, the former name applies to the small- 
leaved perennial vine sparingly grown as a greenhouse climber in 
northern climates and for arbors and trellises in warmer countries. 
Curtis (Bot. Mag. 1797, p. 380) states that it is perennial in Eng- 
land. D. Lablab is generally understood to refer to the common 
hyacinth bean or Bonavist, which has large purple leaves and 
racemes of showy purple flowers and seeds which are mottled 
mahogany brown to black. There are a number of varieties of this 
species, some of which have white flowers, white seeds, and green 
leaves. The size of the seed and the length and compactness of the 
racemes also vary strongly in the different kinds. This plant is 
strictly annual in the United States. It is used as an ornamental 
climber for porches, summerhouses, etc. 
Now Prain (Jour. Asiatic Soc. Bengal 667:429-430. 1897) 
reverses the incidence of these names and makes D. Lablab refer 
to the perennial species and D. lignosus to the annual hyacinth 
bean. 
In the 1895 edition of Index Kewensis, JACKSON does not recog- 
nize Dolichos lignosus as a valid species, but makes D. lignosus 
Jacq. Select. Am. 205 equal D. Jacquini DC. Prod. 2:397, Ind. 
occ.; and he makes D. lignosus Linn. Sp. Pl. 726 equal D. Lablab 
Linn. Sp. Pl. 725, Reg. trop. Again, Prrer (U.S. Dept. Agric. 
Bull. 318. 1915. p. 5), evidently following Pratn and JACKSON, 
accepts the validity of D. Jacquini DC. Prod. 2:397 and assigns 
to this species the small perennial variety of Dolichos formerly 
grown in various parts of the world as D. lignosus Linn. 
These references to LINNAEUS are to the edition of 1753, which 
is now the recognized beginning date of the binomial nomenclature. 
Evidently Linnaeus considered these two species as distinct. If 
Botanical Gazette, vol. 66] [$12 
