VIII. — THE GREAT WATER-PLANTAIN. 
Alisma Plantago-aquatica Linne. 
L INNE seems sometimes to have broken his own rule that the names of species 
should consist of two words only ; but by our existing rules such specific 
names must be written with a hyphen. The result is cumbrous, though far less so 
than was the pre-Linnaean nomenclature. 
The Family Alismace <e — one of the subdivisions of the Order Helobie<e — as we 
limit it, comprises some ten genera and fifty species, widely distributed in all 
climates and in both the Northern and the Southern Hemisphere. It includes some 
floating or largely submerged plants; but the majority of them are, perhaps, like the 
Great Water-plantain, water-side or marsh species. They have generally perennial 
rhizomes, though, as we pointed out when speaking of the Bur-reed, when the 
plants are young the fibrous roots spring apparently direct from the base of the 
upright aerial stem. 
The leaves are generally “radical” in origin; but they vary very much in 
direction of growth and in form, even on the same plant, according to the 
surrounding conditions, whether, that is, they are only liable to be occasionally 
submerged by flood waters, or are constantly floating on the surface, or are 
permanently submerged beneath stagnant or running water. In most cases, 
however, they have long sheathing petioles; and the little axillary stipular scales or 
“ squamulae intravagi nales,” referred to under the last species, are also present. 
The inflorescence is usually much branched and the order of development of 
its successive branchings is somewhat complex, being what is technically termed 
mixed. In this Family the primary branching is racemose and the secondary 
generally cymose, a clear example of which is seen in the Great Water-plantain 
itself. The flowers are mostly conspicuous and polysymmetric, though they may, or 
may not, be perfect. The perianth shows clearly the three-fold symmetry 
characteristic of Monocotyledons, since it is made up of two differing whorls of 
three leaves each, the outer whorl being sepaloid and relatively inconspicuous, while 
the corolla or inner whorl consists of three good-sized petals. The stamens and 
carpels both vary in number from six upwards. The latter are generally superior, 
apocarpous, and one-, or rarely two-, seeded, becoming dry in the fruit stage. The 
ovule is bent on itself like a horseshoe ( campylotropous ), so as to bring its micropyle 
near to its point of attachment and facilitate the entrance of the pollen-tube as it 
grows down from the lower end of the short stylar canal. In those cases in which 
there is only one ovule in each carpel, it rises erect from the base of the ovary, and 
the carpel, when ripe, is indehiscent ; but when there are two or three ovules in 
each carpel, one occupies this position and the others are horizontal, whilst the ripe 
carpel is a follicle dehiscing down its inner side. The seeds are exalbuminous 
and the embryo is curved like the ovule. 
