CHAPTER V 
MONOCOTYLEDONS 
HESE were originally called also Endogens, 
because the wood was thought to increase 
towards the centre. The stem has wood in longitu- 
dinal bundles, isolated, and not, as in Dicotyledons, 
in rings. There is no pith in the centre, defined as 
in Dicotyledons. The leaves usually have parallel 
veins, but in Arum they are reticulate. 
The flowers are in threes or fours, never in fives. 
The embryo has but one cotyledon, and the first 
leaves are alternate. The original radicle is soon 
obscured by the growth of adventitious roots from 
the base of the stem. 
A large proportion are aquatic plants. Asa rule 
they are herbaceous, but a few, such as the Palms, are 
arborescent. 
The leaves are not parallel-veined in Tamus, Paris, 
and are in fours in Naiadaceze, and in Graminez in 
twos and threes. 
The perianth may be petaloid in one group or 
absent. 
PETALOIDEZ. 
The perianth in this group is petaloid and often 
brightly coloured. The perianth is superior in Hydro- 
