[Ill.u.s.tration: Lily of the Valley Leaf]

They all provided themselves with leaves, picking them from the plants and shrubs and trees around them, except Ethel Blue, who already had a lily of the valley leaf with some flowers pinned to her blouse.

"When a leaf has everything that belongs to it it has a little stalk of its own that is called a _petiole_; and at the foot of the petiole it has two tiny leaflets called _stipules_, and it has what we usually speak of as 'the leaf' which is really the _blade_."

They all noted these parts either on their own leaves or their neighbors', for some of their specimens came from plants that had transformed their parts.

"What is the blade of your leaf made of?" Helen asked Ethel Brown.

"Green stuff with a sort of framework inside," answered Ethel, scrutinizing the specimen in her hand.

"What are the characteristics of the framework?"

"It has big bones and little ones," cried Della.

"Good for Delila! The big bones are called ribs and the fine ones are called veins. Now, will you please all hold up your leaves so we can all see each other's. What is the difference in the veining between Ethel Brown's oak leaf and Ethel Blue's lily of the valley leaf?"

[Ill.u.s.tration: Ethel Brown's Oak Leaf]

After an instant's inspection Ethel Blue said, "The ribs and veins on my leaf all run the same way, and in the oak leaf they run every which way."

"Right," approved Helen again. "The lily of the valley leaf is parallel-veined and the oak leaf is net-veined. Can each one of you decide what your own leaf is?"

"I have a blade of gra.s.s; it's parallel veined," Roger determined. All the others had net veined specimens, but they remembered that iris and flag and corn and bear-gra.s.s--yucca--all were parallel.

"Yours are nearly all netted because there are more net-veined leaves than the other kind," Helen told them. "Now, there are two kinds of parallel veining and two kinds of net veining," she went on. "All the parallel veins that you've spoken of are like Ethel Blue's lily of the valley leaf--the ribs run from the stem to the tip--but there's another kind of parallel veining that you see in the pickerel weed that's growing down there in the brook; in that the veins run parallel from a strong midrib to the edge of the leaf."

James made a rush down to the brook and came back with a leaf of the pickerel weed and they handed it about and compared it with the lily of the valley leaf.

"Look at Ethel Brown's oak leaf," Helen continued. "Do you see it has a big midrib and the other veins run out from it 'every which way' as Ethel Blue said, making a net? Doesn't it remind you of a feather?"

They all agreed that it did, and they pa.s.sed around Margaret's hat which had a quill stuck in the band, and compared it with the oak leaf.

"That kind of veining is called pinnate veining from a Latin word that means 'feather,'" explained Helen. "The other kind of net veining is that of the maple leaf."

Tom and Dorothy both had maple leaves and they held them up for general observation.

"How is it different from the oak veining?" quizzed Helen.

"The maple is a little like the palm of your hand with the fingers running out," offered Ethel Brown.

"That's it exactly. There are several big ribs starting at the same place instead of one midrib. Then the netting connects all these spreading ribs. That is called _palmate_ veining because it's like the palm of your hand."

"Or the web foot of a duck," suggested Dorothy.

[Ill.u.s.tration: Tom and Dorothy both had Maple Leaves]

"I should think all the leaves that have a feather-shaped framework would be long and all the palm-shaped ones would be fat," guessed Della.

"They are, and they have been given names descriptive of their shape.

The narrowest kind, with the same width all the way, is called '_linear_.'"

"Because it's a line--more or less," cried James.

"The next wider, has a point and is called '_lance-shaped_.' The '_oblong_' is like the linear, the same size up and down, but it's much wider than the linear. The '_elliptical_' is what the oblong would be if its ends were prettily tapered off. The apple tree has a leaf whose ellipse is so wide that it is called '_oval_.' Can you guess what '_ovate_' is?"

"'Egg-shaped'?" inquired Tom.

"That's it; larger at one end than the other, while a leaf that is almost round, is called '_rotund_.'"

"Named after Della," observed Della's brother in a subdued voice that nevertheless caught his sister's ear and caused an oak twig to fly in his direction.

"There's a lance-shaped leaf that is sharp at the base instead of the point; that's named '_ob-lanceolate_'; and there's one called '_spatulate_' that looks like the spatula that druggists mix things with."

[Ill.u.s.tration: Linear Lance-shaped Oblong Elliptical Ovate]

"That ought to be rounded at the point and narrow at the base," said the doctor's son.

"It is. The lower leaves of the common field daisy are examples. How do you think the botanists have named the shape that is like an egg upside down?"

"'_Ob-ovate_', if it's like the other _ob_," guessed Dorothy.

"The leaflets that make up the horse-chestnut leaf are '_wedge-shaped_'

at the base," Helen reminded them.

"Then there are some leaves that have nothing remarkable about their tips but have bases that draw your attention. One is '_heart-shaped_'--like the linden leaf or the morning-glory. Another is '_kidney-shaped_'. That one is wider than it is long."

[Ill.u.s.tration: Shield-shaped Oblancolate Spatulate Rotund Crenate Edge]

[Ill.u.s.tration: Heart-shaped Kidney-shaped]

"The hepatica is kidney-shaped," remarked James.

"The '_ear-shaped_' base isn't very common in this part of the world, but there's a magnolia of that form. The '_arrow-shaped_' base you can find in the arrow-weed in the brook. The shape like the old-time weapon, the '_halberd_' is seen in the common sorrel."

"That nice, acid-tasting leaf?"

"Yes, that's the one. What does the nasturtium leaf remind you of?"

"d.i.c.ky always says that when the Jack-in-the-Pulpit stops preaching he jumps on the back of a frog and takes a nasturtium leaf for a shield and hops forth to look for adventures," said Roger, to whom d.i.c.ky confided many of his ideas when they were working together in the garden.

[Ill.u.s.tration: Arrow-shaped Ear-shaped Halberd-shaped]

"d.i.c.ky is just right," laughed Helen. "That is a '_shield-shaped_'

leaf."

"Do the tips of the leaves have names?"