448 
AMERICAN JOURNAL OF BOTANY 
[Vol. 10, 
highly self-compatible (M I no. 57), with various intervening grades the 
grouping of which is neither definite nor accurate. 
In these tests mid-styled plants have been more highly self-compatible 
than plants of the other forms. This is true both in relative numbers that 
produce fruit to selfing, and in the range to higher grades of fertility. On 
one plant, M 1 no. 57, every flower that was selfed produced a pod, and four 
other pods were produced in other flowers that spontaneously selfed while 
enclosed in a glassine bag. 
Of the 97 long-styled plants tested in hand-pollinations, only 14 produced 
pods, and not one gave over 30 seeds in any pod. In all of these the self¬ 
compatibility was apparently of a weak grade. 
Twenty-three short-styled plants were tested, and only one produced 
seeds. 
The results obtained in the controlled self-pollinations with these plants 
agree in general with those obtained in isolation tests. A rather large 
proportion of mid-styled plants are self-compatible in some degree, and 
nearly half of the plants of this form produced pods containing viable seeds 
to selfing, and a few were highly self-compatible. There has been no 
difficulty in finding mid-styled plants to use as parents of self-fertilized 
lines of progeny. Relatively few long-styled plants produced pods to self¬ 
ing, and in all such plants the self-compatibility was feeble, few pods being 
produced and these having few good seeds. Short-styled plants have as a 
class been decidedly self-incompatible, and of the seedlings tested only one 
has produced seeds to selfing. The high seed-production seen in the plant 
5 no. 1 in 1919 was not duplicated by the plant in 1918 nor in 1920 and 1921. 
There has not been opportunity to test this plant by controlled hand- 
pollinations as the plants grown from seed have been tested. 
Summary 
1. Many plants of Lythrum Salicaria are capable of producing capsules 
and viable seeds to illegitimate self-pollination brought about either by 
controlled hand-pollination or by insect-pollination in the field. The 
capacity for self-fertilization still lingers strongly in the species. 
2. The proportion of self-compatible plants is greatest in the mid- 
styled plants, in which also the highest grades of self-compatibility are to 
be seen. Long-styled plants are, as a class, less self-compatible, and the 
short-styled plants are still less so. The three forms appear to differ in the 
capacity for self-compatibility. 
3. There are wide variations in the degree of self-compatibility. In 
the most highly self-compatible form, the mid-styled, there are all grada¬ 
tions between complete self-incompatibility and the highest grade of 
self-compatibility. 
4. The variations in the physiological condition of the sex organs, as 
