12 BULLETIN 1167, U. S. DEPARTMENT OF AGRICULTURE. 
tinctly winged, and the leaves are the same as those of the varieties 
previously mentioned. Aerial tubers are borne freely in some years 
and sparingly in others. The tubers are white fleshed, and the 
underground ones are large and of very good table quality. 
In the season of 1920 Mr. Brown grew a much-branched tuber 
weighing 63 pounds, of which previous mention has been made. A 
large piece of tuber was planted in this instance, the plant received 
an abundance of water, and the growing season was longer than 
usual. In 1921 under ordinary field conditions tubers weighing up 
to 8 pounds each were grown at the Brooksville Plant Introduction 
Garden. 
GUAM, OR DAGO HAYA, S. P. I. NO. 39705. 
The Guam yam (PL IX, Fig. 2), or Dago Haya (signifying 
southern, or native, yam), was received in 1914 from Guam through 
Dr. W. E. Safford, of the Bureau of Plant Industry. The variety 
is said to be a favorite in Guam. It is very different from any of 
the other varieties of Dioscorea alata previously described here. 
Both ends of the petiole, or leafstalk, are strongly colored with 
reddish maroon. This feature is very characteristic and furnishes 
an easy means of distinguishing the growing plants of this type 
from those of any of the varieties described on earlier pages. The 
vine is 4-angled, with very narrow maroon wings at the angles. 
The leaf is similar in shape to that of the other varieties mentioned, 
but is of a slightly lighter shade of green. Aerial tubers are seldom 
produced. 
The tubers sometimes grow to a considerable weight, as much as 
28 pounds in rich sandy loam. The behavior of the variety in 
muck has been less satisfactory. In either type of soil large tubers 
are often very rough and of irregular shape and therefore are 
generally undesirable. The inner skin of the Guam yam is deep 
purple, and the white flesh beneath it is frequently tinged irregularly 
with purple. When cooked, the flesh usually becomes distinctly 
grayish and is often very mucilaginous; it is of rich flavor, however, 
and on this account is preferred by some persons to many of the 
whiter varieties. The darkening of this yam when cooked and the 
irregular form of tuber detract from its market value, notwith- 
standing its excellence of flavor. 
S. P. I. NO. 46768. 
This yam is practically identical in vine and leaf characters with 
the Guam variety (S. P.* I. No. 39705), though the maroon color on 
the petioles is not always so pronounced. There are two strains of 
the variety. In one the tubers are apparently identical with the 
Guam yam, while in the other the purple layer in the skin is more 
sharply defined and much thinner. In the latter strain, if the 
purple is all pared away before cooking the flesh remains white; 
this strain is usually more mealy than the other, but it often has 
slightly less flavor. 
PURPLE CEYLON, S. P. I. NO. 54900. 
The Purple Ceylon yam, obtained from the Porto Kico Agricul- 
tural Experiment Station at Mayaguez, is distinguished by the pro- 
duction of tubers usually somewhat spherical in form and with 
deep-purple flesh. The rich color is retained in cooking, and the 
quality of the yam is excellent. This variety was secured by the 
