Fig. 60.

Flower of the Salvia.

I, Half a flower, showing the filament /, the swinging anther a b' a\ and the stigma s, 2. Bee entering the flower pushes the anther so that it takes the position a! b\ No. i, and hits him on the back. 3. Older flower : stigma touching the bee. cut in half, but in the whole flower, one stands on each side just within the lip. Now, when the bee puts her head into the tube to reach the honey, she passes right between these two swinging anthers, and knocking against the end b pushes it before her and so brings the dust-bag a plump down on her back, scattering the dust there ! You can easily try this by thrusting a pencil into any Salvia flower, and you will see the anther fall.

Yon will notice that all this time the bee does not touch the sticky stigma which hangs high above her ^

but after the anthers are empty and shrivelled the stalk of the stigma grows longer, and it falls lower down. By-and-by another bee, having pollen on her back, comes to look for honey, and as she goes into No. 3, she rubs against the stigma and leaves upon it the dust from another flower.

Tell me, has not the Salvia, while remaining so much the same shape as the dead-nettle, devised a wonderful contrivance to make use of the visits of the bee }

The common sweet violet ( Viola odoraid) or the dog violet ( Viola caimid), which you can gather in any meadow, give up their pollen-dust in quite a different way from the Salvia, and yet it is equally ingenious. Everyone has noticed what an irregular shape this flower has, and that one of its purple petals has a curious spur sticking out behind. In the tip of this spur and in the spur of the stamen lying in it the violet hides its honey, and to reach it the bee must press past the curious ring of orange-tipped bodies in the middle of the flower. These bodies are the anthers aa^ Fig. 6i, which fit tightly round the stigma j", so that when the pollen-dust which is very dry, comes out of the bags, it remains shut in by the tips as if in a box. Two of these stamens have spurs which in the coloured spur of the flower, and have honey at rAe end of them. Now, when the bee shakes the end of the stigma s, it parts the ring of anthers, and the fine dust falls through upon the insect.

Let us see foramomenthow wonderfully this flower is arranged to bring about the carrying of the pollen, i.s Sprengel pointed out years ago. In the first place, it hangs on a thin stalk, and bends its head down so that the rain cannot come near the honey in the spur, and also so that the pollen-dust falls forward into the

Fig. 61.

Section of the Dog Violet. Lubbock.

A, A^nthers and stigma enlarged, a a, Anthers, j, Stigma. /, Pollen. ^, Honey. front of the little box made by the closed anthers. Then the pollen is quite dry, instead of being sticky as in most plants. This is in order that it may fall easily through the crackr». Then the style or stalk of the stigma is very thin and its tip very broad, so that it quivers easily when the bee touches it, and so shakes the anthers apart, while the anthers themselves fold over to make the box, and yet not so Rightly but that the dust can fall through when they

are shaken. Lastly, if you look at the veins of the flower, you will find that they all point towards the spur where the honey is to be found, so that when the sweet smell of the flower has brought the bee, she cannot fail to go in at the right place.

Two more flowers still I want us Ao examine together, and then I hope you will care to look at every flower you meet, to try and see what insects visit it, and how its pollen-dust is carried. These two flowers are the common Bird's-foot trefoil {Lotus corfticiclattis), and the Early Orchis [Orchis masculd)^ which you m.ay find in almost any moist meadow in the spring and early summer.

The Bird's-foot trefoil, Fig. 62, you will find almost anywhere all through the summer, and you will know it from other flowers very like it by its leaf, which is not a true trefoil, for behind the three usual leaflets of the clover and the shamrock leaf, it has two small leaflets near the stalk. The flower, you will notice, is shaped very like the flower of a pea, and indeed it belongs to the same family, called the Papilionacece or butterfly family, because the flowers look something like an insect flying.

In all these flowers the top petal {sta^ Fig. 62) stands up like a flag to catch the eye of the insect, and for this reason botanists call it the "standard." Below it are two side-petals w called the "wings," and if you pick these off you will find that the remaining two petals k are joined together at the tip in a shape like the keel of a boat (2, Fig. 62). For this reason they are called the " keel." Notice as we pass that these two last petals have in them a curious little hollow or depression and if you look inside the ''wings" you will notice a little knob that fits into this hollow, and so locks the two together. We shall see by~and-by that this is important Fig. 62.

Lotus corniculahis^ Bird's-foot Trefoil.

I. Full flower: sta^ Standard; Wings; Keel. 2. Keel of flower: Depression into which wings fit, 3. Interior of flower:

Stigma ; Pollen ; Anthers ; Place where honey lies.

Next let us look at the half-flower when it is cut open, and see what there is inside. There are ten stamens in all, enclosed with the stigma in the keel nine are joined together and one is by itself. The anthers of five of these stamens burst open while the flower is still a bud, but the other stamens go on growing, and push the pollen-dust, which is very moist 16

and sticky, right up into the tip of the keel. Here you see it lies right round the stigma Sy but as we saw before in the geranium, the stigma is not ripe and sticky yet, and so it does not use the pollengrains.

Now suppose that a bee comes to the flower. The honey she has to fetch lies inside the tube at h, and the one stamen being loose she is able to get her proboscis in. But if she is to be of any use to the flower she must uncover the pollen-dust. See how cunningly the flower has contrived this. In order to put her head into the tube the bee must stand upon the wings w, and her weight bends them down. But they are locked to the keel k by the knob fitting in the hole and so the keel is pushed down too, and the sticky pollen-dust is uncovered and comes right against the stomach of the bee and sticks there ! As soon as she has done feeding and flies away, up go the wings and the keel with them, covering up any pollen that remains ready for next time. Then when the bee goes to another flower, as she touches the stigma as well as the pollen, she leaves some of the foreign dust upon it, and the flower uses that rather than its own, because it is better for its seeds. If however no bee happens to come to one of these flowers, after a time the stigma becomes sticky and it uses its own pollen : and this is perhaps one reason why the birds-foot trefoil is so very common, because it can do its own work if the bee does not help it.

Now we come lastly to the Orchis flower. Mr. Darwin has written a whole book on the many curious and wonderful ways in which orchids tempt bees and othei insects to fertilize them. We can only take the simplest, but I think you will say that even this blossom is more like a conjuror's box than you would have supposed it possible that a flowV could be.

Let us examine it closely. It has six deep-red covering leaves, three ccc, Fig. 63, belonging to the

Fig. 63.

Orchis mascula,

c c Calyx, co^ co^ cOy Corolla. /, Pollen-masses, r, Rostellum or lid covering the knob at the end of pollen-masses, s s, Stigmas. P, a Pollinia or pollen-mass, of which a is the pollen and d the sticky gland which adheres to the head of the bee. sv. Seed-vessel, sp^ Spur of the flower. calyx or outer cup, and three cOy cOy cOy belonging to the corolla or crown of the flower ; but all six are coloured alike, except that the large one in front,

called the "lip/' has spots and lines upon it which will suggest to you at once that they point to the honey.

But where are the anthers, and where is the stigma ? Look just under the arch made by those three bending flower-leaves, and there you will see two small slits, and in these some little club-shaped bodies p/, which you can pick out with the point of a needle. One of these enlarged is shown at P. It is composed of sticky grains of pollen a held together by fine threads on the top of a thin stalk ; and at the bottom of the stalk there is a little round body This is all that you will find to represent the stamens of the flower. When these masses of pollen, or pollinia as they are called, are within the flower, the knob at the bottom is covered by a little lid r, shutting them in like the lid of a box, and just below this lid r you will see two yellowish lumps s Sy which are very sticky. These are the top of the stigma, and they are just above the seed-vessel sVy which you can see in the lowest flower in the picture.

Now let us see how this flower gives up its pollen. When a bee comes to look for honey in the orchis, she alights on the lip, and guided by the lines makes straight for the opening just in front of the stigmas ss. Putting her head into this opening she pushes down into the spur spy where by biting the inside skin she gets some juicy sap. Notice that she has to bite, which takes time.

You will see at once that she must touch the stigmas in going in, and so give them any pollen she has on her head. But she also touches the little lid r and it Jlies instantly openy bringing iJie glands d at the end of the pollen-masses against her head. These glands are moist and sticky, and while she is gnawing the inside of the spur they dry a little and cling to her head and she brings them out with hen Darwin once caught a bee with as many as sixteen of these pollen-masses clinging to her head.

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