I9I4- 
Rid D E i,SDKiyiv. — Hdoscia dmni Moorcu 
5 
In the /ns/i Naturalist, of 1912, p. 235, Mr. Driice gave 
publicity to the fact that ho and Hcrr (jliick had considered 
the question of hybridity. It is, however, part of my purpose 
in this paper to advance good reasons for supporting the 
theory of hybridity. In doing so, I am aware that the 
theory cannot be proved. Most Hkely it cannot be disproved 
either ; for even if actual experiment should succeed in 
producing a cross between the two species Helosciadium 
inundatum and nodiflorum which should be quite different 
from Moorci, that is very doubtfully conclusive as to what 
may happen under the freely working and unartificial con- 
ditions of nature. Of course, if artificial cross-breeding 
produced Moorei, it would add very strongly to the pro- 
bability of the latter being, in its natural habitats, also a 
true hybrid in origin. But beyond probabihty it is (I 
believe) impossible to go in this case. There are, however, 
as will be shown, strong reasons for the probable conclusion 
that A. Moorei is a hybrid between A. immdaUim and A. 
nodiflorum. To this effect I wrote to Dr. Gliick in October, 
1912, and when he saw my reasons he was quite ready to 
agree with me. 
The plant may be described as follows : — 
Root perennial, consisting of long white fibres. Stem 
often rooting freely from its lower joints, and even to 
within two or three joints of the extremity. The autumn 
form of the plant is, as in H. nodiflorum, a tuft of leaves. 
Plant light green, glabrous ; very variable in size (6 to 
30 inches). 
Stem generally weak, usually erect in the water, or 
smaller, more decumbent, and rather stronger. Much 
branched from near the base of the stem with long erectish 
axillary branches ; surface of stem lightly furrowed. 
Leaves pinnate and very varied. 
Upper leaves with 7-9 leaflets ; leaflets broadly ovate 
or obovate to narrowly lanceolate or oblanceolate, or 
narrowly elliptic. Leaflets variously cut ; sometimes with 
a few broad, blunt teeth, one or two of which may actually 
form lobes (especially in the case of the broader U^ath^ts) ; 
narrower leaflets cut into narrower and acuter teeth, and 
sometimes into narrow, acute lobes, sometimes even into 
three subequal lobes. 
