Showy ladies' slipper.
Photo by Verne Morton.
"Graceful and tall the slender drooping stem,
With two broad leaves below,
Shapely the flower so lightly poised between,
And warm its rosy glow."
These showy flowers look so strange in our woodlands that we gaze at them as curiously as we might upon a veiled lady from the Orient who had settled in our midst. There is something abnormal and mysterious in the shape of this flower, and though it be called the lady's slipper, yet it would be a strange foot that could fit such a slipper; and if it is strange at the first glance, it is still more so as we try to compare it with other flowers. There are two long sepals that extend up and down, the lower one being made up of two grown together—but the "seam" does not show. The sepals are yellow, and are wider than the two long streamers that extend out at right angles to them, and which are petals; the brighter color of the latter, their markings of reddish dots, the hairs near their bases, all go to show that these petals, although so different in shape, belong to the same series as the big lower petal which is puffed out into a sac, shaped like a deep, long bowl, with its upper edges incurved. If we look carefully at this bowl, we find two openings besides the main one; these two are near the stem, and their edges are not incurved. Extending out into each of these openings is a strange little round object, which is an anther; but if we try to get pollen from this anther with a pencil or a knife we get, instead of powdery pollen, a smear that sticks to what it touches, like melted rubber or gum. The secret of this is, that the lower side of the anther is gummy, and adheres to whatever touches it and brings with it, when pulled away, the mealy pollen which lies loose above it. Another strange thing is that, if this lower part of the anther is not carried away, it seems to partially harden and opens downward, letting the pollen escape in a way usual with other flowers. We have to remove a side of the bowl to see the stigma; it is fan-shaped, and is bent at right angles to the flower stem; and above it, as if to protect it, is a stiff triangular piece which is really a strangely modified stamen. I think one reason why the lady's slipper always is called "she" is because of this tendency on her part to divert an object from its natural use. Surely a hairpin used for a paper knife or a monkey-wrench for a hammer, is not nearly so feminine a diversion as a stamen grown wide and long to make an awning above a stigma.
The general color of the flower is yellow, and there are some seductive dark red spots on the stamen-awning and along the folded-in surface of the petal-sac which say plainly, "Come here, Madam Mining-bee, and see what these spots mean." And the little bee alights on the flower and soon crawls into the well at the center, the recurved edges preventing it from returning by the same door. At the bottom of the sac there are delectable vegetable hairs to be browsed upon; if there is nectar, I have never been able to detect it with my coarse organs of taste; and Mr. Eugene Barker, who has examined hundreds of the flowers, has not been able to detect the presence of nectar in them at any stage; but he made no histological study of the glands.
Detail of yellow lady's slipper.
1. l, leaf; s,s, sepals; p,p, petals; p.s., petal-sac.
2. Side-view: ac, anther cover; p.s., petal-sac; a, anther. The arrow shows the path of the insect.
3. an, anther closed; o, anther open.
After a satisfying meal the bee, which is a lively crawler, seeks to get out where it sees the light shining through one of the openings near to the stem. In doing this, she presses her head and back, first against the projecting stigma and then against the sticky anther, which smears her with a queer kind of plaster; and it sticks there until she brushes it off on the stigma of another flower, when crowding past it; and there she again becomes smeared with pollen plaster from this flower's anthers. Mr. Barker, who has especially studied these flowers, has found that the little mining bees of the genus Andrena were the most frequent visitors; he also found honey-bees and one stray young grasshopper in the sacs. The mining bees which he sent to me had their backs plastered with the pollen. Mr. Barker states that the flowers are not visited frequently by insects, and adds feelingly: "My long waiting was rewarded with little insect activity, aside from the mosquitoes which furnished plenty of entertainment."
The ovary looks like a widened and ribbed portion of the flower-stem, and is hairy outside; its walls are thick and obscurely three-angled; seen in cross-section the seeds are arranged in a triangular fashion which is very pretty.
The leaves of the yellow lady's slipper are oval or elliptic, with smooth edges and parallel veins; they often have narrow veins between each two heavier ones. The leaves are of vivid yellowish green and are scattered, in a picturesque manner, alternately along the stem, which their bases completely clasp. The stem is somewhat rough and ribbed and is likely to grow crooked; it grows from one to two feet in height. The roots are a mass of small rootlets. The species is found in woods and in thickets.
The pink moccasin flower, also called the stemless lady's slipper (C. acaule), is perhaps prettier than the yellow species, and differs from it in several particulars. The sac opens by the merest crevice, and there are plenty of dark-pink guiding lines which lead to the little opening of the well. The downward-folded edges prevent the visiting insect from getting out by this door even more surely than in the other species. The side petals are not so long as in the yellow species, and they extend forward as if to guide the insect to the well in the lower petal. The sepals are greenish purple, and are likewise shorter; and the lower one is wide, indicating that it is made up of two grown together. At the base of the ovary there is a pointed green bract or leaf, which lifts up and bends above the flower. There are but two leaves on the stemless lady's slipper; they arise from the base of the stem. They are broadly ovate, and from six to seven inches long. This species grows in sandy or rocky woods.
Another species more beautiful than these is the showy lady's slipper, which is white with a pink entrance to the petal sac. This grows in peaty bogs, and is not so common as the others.
The interesting points for observation in these flowers are the careful noting of the kinds of insects which visit them, and how they enter and leave the "slipper," or sac.
Leading thought—The moccasin flower belongs to that family of flowers known as orchids which especially depend upon insects for bringing and carrying pollen, and which have developed many strange devices to secure insect aid in pollenation.
Method—A bouquet of lady's slippers should be brought to the schoolroom. Children who bring them should describe the place where they were found.
1. Where does the yellow lady's slipper grow? Look carefully at its leaves and describe them. How do they join the stem? Are they opposite or alternate?
2. What is there peculiar about the sepals? How many are there?
3. Describe the three petals and the difference and likeness in their form and color. What is the shape of the lower petal? Is there a hole in this sac? Is there more than one hole leading into it? What is the color of the sac? Is there anything about it to attract insects? If an insect should enter the mouth of the well in the lower petal could it easily come out by the same opening? Why not? Where do you think it would emerge?
4. Note the two roundish objects projecting into the two openings of the sac near the stem. Thrust a pencil against the under side of one of these. What happens? How does this pollen differ from the pollen of ordinary flowers?
5. Cut away one side of the petal-sac and find the stigma. What shape is it? Where is it situated with relation to the anthers? How is the stigma protected above? Where is the ovary, or seed-box?
6. Explain how a bee visiting these flowers, one after another, must carry the pollen from one to another and deposit it on the waiting stigmas.
7. How is the insect attracted? How is it trapped and made to do the work?
8. Look at the seed-capsule and describe it from the outside. Cut it across, and describe the arrangement of the seeds. How many sides of the seed-capsule open, to let loose the seeds?
9. How many species of lady's slippers do you know? Do you know the pink, or stemless species? How does it differ from the yellow species in the following particulars: The shape of the sac; its color and markings; the length and shape of sepals; the number and position of the leaves.