Myriophyllum."\ XXXIV. HALORAGM. 173 



Stamens 4 or 8. Stigmas and seeds 4 1. Mykiophyllum. 



Stamen, stigma and seed 1 2. Hippuris. 



I. MYRIOPHYLLUM. WATER-MILFOIL. 



Aquatic plants, with finely pinnated, whorled leaves, and minute, 

 sessile, monoecious flowers. Calyx with 4 short divisions. Petals 4 in 

 the male flowers, very minute or none in the females. Stamens in the 

 males 8, 6, or 4. Ovary and capsule of the females short, divided into 

 4 cells, with 1 seed in each. 



A small genus, widely diffused over almost every part of the globe. In 

 its finely-cut whorled leaves it bears at first sight much resemblance to 

 Ceratophyllum, but the lobes of the leaves are pinnate, not repeatedly 

 forked as in the latter plant. 



Floral leaves or bracts not longer than the flowers . . . 1. M. spicatum. 

 Floral leaves longer than the flowers, usually pinnate like the 



stem-leaves . 2. M. verticillatum. 



1. M. spicatum, Linn. (fig. 395). Spiked M. — Rootstock perennial, 

 creeping and rooting in the mud under water. Stems ascending to the 

 surface, but usually wholly immersed, varying in length according to 

 the depth of the water, and more or less branched. Leaves whorled, in 

 fours or sometimes in threes or in fives, along the whole length of the 

 stem ; the numerous capillary segments entire, 3 to near 6 lines long. 

 From the summit of the branches a slender spike, 2 to 3 inches long, 

 protrudes from the water, bearing minute flowers arranged in little 

 whorls, and surrounded by small bracts seldom as long as the flowers 

 themselves. The upper flowers are usually males, their oblong anthers, 

 on very short filaments, protruding from the minute calyx and petals. 

 The lower ones are female, very small, succeeded by small, nearly globular 

 or slightly oblong capsules, each separating ultimately into 4 1-seeded 

 carpels. 



In watery ditches, and ponds, throughout Europe and Russian Asia. 

 Extending all over Britain. Fl. all summer. A slender variety, with 

 the whorls of the spike often reduced to a single flower, and the lower 

 ones having leaves at their base like the stem-leaves, has been considered 

 a distinct species, under the name of M. alterniflorum, DC. 



2. M. verticillatum, Linn. (fig. 396). Whorled M. — In deep, clear 

 waters, the foliage is precisely that of M. spicatum, but the flowers are 

 all immersed in the water, in the axils of the upper leaves. In shallow, 

 muddy ditches, the segments of the leaves are often shorter and fewer, 

 and the flowers form a spike protruding above the water as in M. spicatum, 

 but the bracts or floral leaves are longer than the flowers, and pinnate 

 like the stem-leaves : this form constitutes the M. pectinatum of some 

 authors, but cannot be distinguished with any precision, even as a 

 variety. 



In watery ditches and ponds, with M. spicatum, over the greater part of 

 its geographical range, and in many countries as common. In Britain it 

 appears to be rather scarce, but perhaps frequently overlooked from its 

 flowers not appearing above the water. Fl. all summer, [M. pectinatum, 

 DC, is a variety with very short floral leaves.] 



