BULLETIN 
OF THE 
TORREY BOTANICAL CLUB. 
Vol. X.l New York, April, 1883. [No- 4 
Notes on the Haustoria of some N- A. Parasitic Phanerogams. 
By Jos. SCHRENK. 
(Plates xxxi-xxxiii.) 
CoMANDRA UMBELLAXA, Nutt. — The following description of 
the haustorium of Comandra is based on specimens that grew on the 
roots of Aster Tradescanti, L. The figures on the accompanying 
plates (except Fig. 5), were all drawn from such haustoria; those 
from other dicotyledonous foster-plants, however, are not at all 
esseritially different. In Figs. 3, 6 and 8 the outlines of the various 
tissues are magnified 80 times, while the individual cells are made to 
represent the type of those tissues by employing higher powers. In 
the figures of the other sections the cells appear magnified about 500 
times, and the perspective illustrations of the entire haustorium with 
its foster-root, Figs, i^, ib, and 2a, 2I?, 8 and 12 times respectively. 
For the sake of brevity, I shall, with reference to the foster-root, call 
the sections represented by Figs. 3, 6 and 8 respectively, the longi- 
tudinal, the transverse, and the tangential (the last being a cross- 
section of the haustorium itself). 
The haustoria (suction-organs) of Comaiidra grow on thin, short 
branches of the root, and usually appear as if stalked. Sometimes 
they seem to be terminal (Fig. 2^), but their internal structure, as 
well as the common mode of their growth, illustrated by Fig. la^ 
show that they are lateral organs. The rootlet bearing the hausto- 
rium may run parallel with the foster-root (Fig. \a), or in a different 
direction (Fig. 2a). The form of the haustoria is half-ellipsoidal or 
bell-shaped, somewhat laterally flattened, the longer diameter of their 
cross-section being parallel with the axis of the foster-root. Their size 
varies according to age and other circumstances. The smallest are 
quite minute ; the ones figured on the plates (a little over i™"*' high 
and about i.5"'°'- wide), I found to be of a common size, but there 
are some that are twice as large, or even larger. 
Viewed externally, the haustorium appears to grasp the root of 
the foster-plant as a hand, deprived of its thumb, would grasp a large 
cylindrical object; or, still better, as one's lips would take hold of a 
finger-joint to suck the blood from a wound (Figs. \a, \b, 2a, 2b). ^ 
in describing the structure of the haustorium, we have to distin- 
guish the interior tissues, which penetrate into the body of the foster- 
root, from the external covering. The latter, which we might call 
the bark of the haustorium {bk in all the figures), reaches from the 
top of the haustorium to the bark of the foster-root, which it partly 
encircles, thus playing the part of the lips in the above comparison. 
At its lower edge, we find a number of papillose cells, reaching, or 
