Abstract:

 Acanthochlamydoideae, a new subfamily of Amaryllidaceae, is proposed in the pre-

sent paper, based upon the monotypic genus Acanthochlamys which was detected by

the writer in 1979 and named Didymocolpus as a new genus but was preceded by P. C.

Kao in 1980 under the former name.  The genus is indeed of great morphological in-

terest. It has semicylindric leaves with a deep furrow on the ventral and dorsal sides

respectively.  The lower part of the leaf is connate with, or adnate to, the lower mid-

rib of a rather large and membranous vagina . Such a feature, as far as we know, is

very rare in the monocotyledons.

     The flower resembles that of Amaryllidaceae in having inferior ovary, six stamens

and corolla-like perianth with a rather long tube.  But it is quite different in other

characters, such as head-like cyme, leaf-like bracts and bisulcate leaves, which all are

foreign to any taxon known in the Amaryllidaceae.  On the other hand, it bears some

resemblance particularly in habit and inflorescence  to  Campynemanthe  of  the Hy-

poxidaceae, and also to Borya and Bartlingia of the Liliaceae (in the tribe John-

sonieae), but differs in its long perianth-tube and curious leaf structure.  It is highly

probable that the resemblance between them is only superficial and not indicative of

direct or close relationship.

     This is no doubt a very curious plant of which we still know incompletely, and

for which an appropriate place in the monocotyledons has not yet been found.  Con-

sidering its floral characters, however, it seems safe for the present to place it as a

separate subfamily in the Amaryllidaceae and is juxtaposed with the Ixiolirioideae

and Amaryllidoideae, the only two subfamilies of Amaryllidaceae according to H. Mel-

chior (1964), and, of course, to either of them it is not directly related. Its true affinity

remains problematic.

     The only species, Acanthochlamys bracteata, is found in Mar-er-kan (102°12'N,

31°47'E), Qian-ning (101°30'N, 30°33'E), Xiang-cheng  (99°39'N, 28°54'E)  and Dau

cheng (100°10'N, 29°03'E) in western Sichuan of southwest China, in open bushland

or grassland at an altitude between 2700—3500 meters.  Its geographical distribution is

mapped and its morphological details are illustrated to facilitate its identification.