Photo by Cyrus Crosby.
During April, great patches of blue appear in certain meadows, seeming almost like reflections from the sky; and yet when we look closely at the flowers which give this azure hue to the fields, we find that they are more lavender than blue. The corolla of the bluet is a tube, spreading out into four long, lavender, petal-like lobes; each lobe is paler toward its base and the opening of the tube has a ring of vivid yellow about it, the tube itself being yellow even to its very base, where the four delicate sepals clasp it fast to the ovary until the flower has done its work; and after the corolla has fallen the sepals remain; standing guard over the growing seed.
If we look carefully at the bluets we find two forms of flowers: (a) Those with a two-lobed stigma protruding from the opening of the flower tube. (b) Those where the throat of the tube seems closed by four anthers which join like four fingertips pressed together. In opening the flower, we observe that those which have the stigmas protruding from the tube, have four anthers fastened to the sides of the tube about half-way down; while those that have the four anthers near the opening of the tube, have a pistil with a short style which brings the stigmas about half-way up the tube. Thus an insect visiting flower (a) gets her tongue dusted with pollen from the anthers at the middle of the tube; and this pollen is applied at exactly the right place on her tongue to brush off against the stigmas of a flower of the (b) form. While a bee visiting a bluet of the (b) form receives the pollen at the base of her tongue, where it is conveniently placed to be brushed off by the protruding stigmas of the flowers of the (a) form.
1. Section of a bluet blossom that has the anthers at the throat of the tube and the stigmas below.
2. Section of a bluet with the stigmas protruding and the anthers below.
This arrangement in flowers for the reciprocal exchange of pollen characterizes members of the primrose family also; it is certainly a very clever arrangement for securing cross-pollenation.
Leading thought—The bluets have two forms of flowers, the anthers and stigmas being placed in different positions in the two, in order to secure cross-pollenation by visiting insects.
Method—Ask the children to bring in several bits of sod covered with bluets. During recess let the pupils, with the aid of a lens if necessary, find the two different forms of flowers. Later, let each see a flower of each form with the tube opened lengthwise.
1. Where do the bluets grow? Do they grow singly or in masses? On what kind of soil do they grow, in woods or meadows? At what time of year do they bloom?
2. Describe the bluet flower, its color, the shape of its sepals, the form of the corolla, the color of the corolla-tube and lobes.
3. Where is the nectar in the bluet? What color shows where the nectar is to be found?
4. Look directly into the flowers. Do you see any with the stigmas thrust out of the corolla-tube? Is there more than one style? Has it one or two stigmas? Open this flower-tube and describe where the anthers are situated in it. How many anthers are there?
5. Look for a flower where the stigmas do not protrude and the anthers close the throat of the tube. Where are the stigmas in this flower, below or above the anthers? Where are the anthers attached?
6. Work out this problem: How do the insects gathering nectar from one form of the bluets become dusted with pollen in such a way as to leave it upon the stigma of the other form of the bluet flower?
7. How many sepals are there? Do they fall off when the blossom falls?
"So frail, these smiling babies,
Near mossy pasture bars,
Where the bloodroot now so coyly
Puts forth her snowy stars;
And the maple tall and slender,
With blossoms red and sweet,
Looks down upon the bluets
Close nestled at her feet.
'Innocents', the children call them,—
These floral babies small,
Of Mother Nature olden,
Whose broad lap holds them all."