To George Bentham   12 July 1877

My dear M^r Bentham,

I am very much obliged for your corrections about Cleistogamic Plants.— I have great confidence in Gärtner, & my statement was founded on what he says, supported by other observations. He adds that his rule does not apply to cultivated plants, & I should not expect that it would hold good with variable plants in a state of nature. As Verbascum does not I think vary much I was surprised at the case which I record. Your facts clearly show that the rule is very far from always holding good.¹

My son Francis & I are trying to make out the function of bloom or waxy secretion on leaves fruit &c of plants; but I much doubt whether we shall succeed.² It would be a guide to us if you have any decided opinion whether bloom-producing plants are more common under a hot or cold climate, under a dry (such as in Australia or the Cape of Good Hope) or rainy climate. Judging from the plants of England, the species which grow close to the sea seem to be often covered with bloom. If you can give us any hints we should be greatly obliged.

Believe me, my dear M^r Bentham | Yours sincerely | Charles Darwin