212 TUE (EXOTHEEA. FAMILT. 



1. Spiked Myriophyll. Myriopliylluin spicatum, Linn. 

 (Eug. Bot. t. 83. Water Milfoil.) 



Kootstock perennial, creeping and rooting in the mud under water. 

 Stems ascending to the surface, but usually wholly immersed, varying iu 

 length according to the depth of the water, and more or less branched. 

 Leaves whorled, in fours or sometimes in threes or iu fives, along tlie wliole 

 length of the stem ; the numerous capillary segments entii-e, 3 to near 6 lines 

 long. From the summit of the bi'anches a slender spike, 2 to 3 inches 

 long, protnides from the water; bearing minute flowers arranged in little 

 whorls, and surrounded by small bi-acts seldom as long as the flowers them- 

 selves. The upper flowers are usuuUy males, their oblong anthers, on very 

 short filaments, protruding from the minute calyx and ]3etals. The lower 

 ones are female, very small, succeeded by small, nearly globular or slightly 

 oblong capsules, each separating ultimately into 4 one-seeded carpels. 



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

 tending all over Britain. Fi. all summer. A starved slender variety, with 

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

 ones having leaves at theii* base like the stem-leaves, has been considered by 

 some as a distinct species, under the name of M. alteruijlorum (Eng. Bot. 

 Suppl. t. 2854). 



2. TVhorled Myriophyll. Myriophyllum verticillatum, Linn. 

 (Eng. Bot. t. 218. Water Milfoil.) 



In deep, clear waters the foliage is precisely that oi the spiTced M ., but the 

 flowers aj-e all immersed in the water, in the axils of the upper leaves. In 

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

 fewer, and the flowers form a spike protruding above the water as in the spiked 

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

 like the stem-leaves : this form constitutes the 31. pectinatum of some au- 

 thors, but cannot be distinguished with any precision, even as a variety. 



In watery ditches and ponds, with the spiked M., 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. Ft. all summer. 



VI. MARESTAII.. HIPPURIS. 



A single aquatic species, distinguished as a genus from Myriopliyll by its 

 entu-e leaves, and by its flowers always without petals, with a scarcelv per- 

 ceptible border to the calyx, and reduced to 1 stamen, 1 subulate style, and 

 1 ovule and seed. 



1. Common jMCarestail. Hippuris vulgaris, Linn. 

 (Eng. Bot. t. 763.) 

 An aquatic plant with a perennial rootstock, and erect, annual, simple 

 stems, the upper part projectmg out of the water sometimes to the height of 

 8 or 10 inches, and crowded in tlieir whole length by whorls of fi-om 8 to 12 

 linear entire leaves ; the submerged ones, when in deep streams, often two or 

 three laches long, gradually dimmishing tiU the upper ones are less than half 

 an mch. Flowers minute, sessile in the axils of the upper leaves, consistLug 



