182 THE Ottawa NarTurAListT. | December 
Here are a few additional—questions relating to water lilies 
which the nature student should try to answer. In what respects 
are the leaves. flowers, and rootstocks. of the white and yellow 
water-lilies alike ? In what respects do they differ? What is the 
function of the air-canals in the petioles and peduncles? Why is 
the upper suface of the leaf waxy ? Determine on which surface of 
the leaf the stomates or breathing pores are placed. Do the sub-_ 
merged rootstocks bear leaves? What hold the rootstalks at the 
bottom? Account for the numerous scars on a rootstock. What 
is the color of the rootstock ? In what part of the rootstock are 
the strengthening tissues located? What differences in the habits 
of the tlowers of the two species? What changes occur to the 
pistil when it is mature? What insects visit the flowers ? What 
are the insect enemies of pond-lilies ? 
Other plant formations may be studied in the ground around 
the house. At the back door where there is abundant nitro- 
genous waste are knot-weeds, lamb’s quarters, chickweeds, large- 
leafed plantains, burdocks, ragweeds, shepherd’s purse, docks, 
and nettles. All are hardy, quick-growing, and prolific in seeding. 
Here again are special adaptations. The stem of the large- 
leaved plantain is actually pulled down a short distance into the 
ground by its many contractile roots, and the plant is better pre- 
served from injury than if it lifted its stem into the air. The 
chickweed leaves have lines of hairs which direct the rain 
which falls on them down the stem to the roots. The pointed 
leaf of the nettle, on the other hand, directs the rain away from. 
the stem, and allows it to drip from the tips of the outside leaves 
to the ground. The roots of the nettle spread widely, and the rain 
falls where it will be most refreshing. The docks and burdocks 
have deeply penetrating roots, and they seldom suffer from lack of 
moisture. : 
Beneath the trees the plants are mainly blue grasses. There 
the vegetation is so rank and close that other plants have but 
little chance to make headway. Sometimes rib-grass, yarrow, and 
ox-eye daisy establish themselves, but these, it will be noted, have 
leaves either narrow like the grasses themselves, or dissected so 
that they can compete with the grasses. The grass leaf shows an 
daptation to rain. When rain falls the water running down the 
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