IN PLANTS HAVING IRREGULAR COROLLAS. 401 
type (Plate LI. fig. 6) the three segments of the outer whorl are 
so disposed that one of them (3) is anterior and median, while the 
other two (1 & 5) are posterior and lateral ; in this type, therefore, 
the median plane of the symmetry bisects the anterior segment 
longitudinally. The segments of the inner whorl, on the contrary, 
are arranged in a complementary manner, so that the single 
posterior petal (6) is median while the other two (2 & 4) are antero- 
lateral. In both cases a stamen stands in the middle plane of the 
symmetry ; but in Type I. the median stamen is anterior, while 
in Type II. it is posterior. The symmetry of the second type 
seems to be that of the first inverted, for in Type IT. the anterior 
petal of the inner whorl is median, while the two others are 
postero-lateral. The outer whorl is therefore placed so that the 
posterior segment is median and the other two are antero-lateral. 
Between these two types there are certain intermediate forms 
which will be described later. 
The two types of flower may be found together on the same 
spike, or a whole spike may bear only flowers of one type. In 
cases in which both types occur together, it sometimes happens 
that one side of the spike bears flowers of one type, and the 
other bears flowers of the other type; in other cases, the two 
types occur more or less alternately on the two sides, but more 
usually no definite arrangement is followed. Flowers of both 
types, when on the same spike, are coloured alike, no matter 
what the colours of the spike may be; the distribution of the 
colouring in the two types differs in the manner to be described. 
In flowers of Gladiolus it is usual for some of the anterior 
segments to be narrower than the rest, of a claw-like form, and 
of a colour different from that of the other segments. This 
difference in colour takes the form of either a striping or of a 
rhomboidal patch of dark or light colour upon the claw-like 
segments. The number of segments thus marked is partly 
dependent on whether the flower is of Type I. or of Type II. 
In flowers of Type I. (which may be said at once to be the 
normal form of most, if not all, wild Gladiolus) either all three 
anterior segments 2, 3, and 4 are thus marked, or only 2 and 4 
have this feature; but in Type Il. either 2 alone may be marked 
or 1, 2, and 3 may all be marked. But if a spike bears flowers 
of both types, and those of Type I. have only 2 and 4 marked, 
the flowers of Type II. on the same spike will have only 2 
marked. 
