My dear Mr Darwin

Hurrah for Coronilla! C. montana—a smaller & more delicate plant than our old C. varia has no possible nectar inside the flower—but the calyx is covered with minute cells full of liquid— Many aphides on them.²

C. Emerus (lutescens)³ has the same general structure as the others: but elongated— The calyx has no moisture on the outside but the staminal tube ends at the base in a regular nectar cavity with apertures on each side like a pea: the cavity full of nectar. C. Emerus—the common form will be in full blossom soon & I hope to see bees at it.

In C. Emerus lutescens there is a curious projection on the inside of the claw of the vexillum.⁴ I suspect it tells the bee that it must put its nose—quite out of its sight—to the right or left in order to get to the nectar holes. But if this is all true I dont know why the bee should not go in by the back door. Nous verrons.⁵

At any rate here is a case where in the same genus all have a free tenth stamen— some have as usual in that case nectar in the staminal tube— others have not the nectar there—but have it outside the calyx with a peculiar arrangement of the petals enabling the bee to get at it there.

This helps to explain the free 10^th stamen; serviceable in some, rudimentary in others.

Your son should look at the projection on the claw of C. Emerus lutescens.⁶

Poor Effie⁷—so seldom laid up has been in misery with a bad tooth and is gone up with Hope⁸ to get rid of it. This damps our owise pleasant Easter in the new house

Yrs most truly | T H Farrer

Which came first—free 10^th stamen or peculiar aperture at base of petals?