From Charles Wright to Asa Gray 20, 25, and 26 March and 1 April 1864
March 20th 1864
My Dear Dr.
I received a few days ago yours of the 16th ult. containing Dr. Hooker’s note which I have answered so much at length that perhaps he’ll dub me a “bore” but I felt that I could not well reply to his questions without doing so.1 I shall trust to your kindness to forward it when you have occasion to write a line yourself.2 We are now about at the end of the dry season.3 The savanas are now newly burnt over & yield nothing. Forest trees are changing their attire: some are flowering[.] Orchids & Tillandsias begin to grow anew. I have at last found one (orchid) in some respects more remarkable than those so graphically described by Mr. Darwin—4 sorry I cant give you the name tho’ I believe it is in my collections5 The stigmatic surfaces are very sticky & are widely separated by the rostellum which projects downwards or even a little backwards if any thing but nearly parrallel with the column which is thick & short (proportionally) The downward movement of the pollinia is almost instantaneous so that I extracted a number without discovering it till I did it under the microscope. Sometimes it is slower sometimes quicker (according to the age of the fl. or time of day?) but it always ends with a jerk through – of the arc of about 90°. After depression the disk & pedicels are just like the fig. of Gymnadenia conopsea—Darwin, p. 80.6 I say pedicels, for in this case the pedicels are connate into a strap-shaped organ (white—the disk is brownish) to the tip of which the minute oval pollen masses are attached by a point nearly at right angles but diverging laterally so as better to enter the stigmatic cavities though they appear to me to be at last some what too close together for that. However they stick well when introduced into the same or another fl. And they are so firm that they either remain bodily or are drawn out again which however rarely happens according to the few trials I have made. The lip is furnished with two prominent tubercular crests between which the proboscis of the insect must pass to reach the nectar in the minute sack at its base.7
Day after tomorrow I expect to go to the coast (south) for two or three or more days if I find many things to collect This is the season when the people eat fish (flesh being prohibited)8 & a neighbor of friend Blain9 goes to improve the fiesta and make a little money by the sale of his “catch” & at the same time obey the precepts of his church & the dictates of his conscience!!! He used to be engaged in the slave trade smuggling & piracy a little I believe. I have long wanted to visit that coast for a short herborisation & once knowing the way I can return if it promises much for another & more favorable season of the year
It is pretty dry though the grass is not yet very short and a pretty good shower came the other night to give it a start. My horses are in good condition against the time when I shall want to set out on some long tour. I proposed to Gundlach a run to the north in the summer after making our excursion westward.10 He says he can’t go yet, but I am inclining more & more to go it alone if he wont accompany me. I have twice traversed the western end of the island in the latter part of the year, & after a spring excursion through the same places I might well afford to spend a few months visiting my friends & equipping myself anew for another two or three years absence fr. home & residence in the island. We have dates fr. New York on the 12th inst11 & am beginning to fear that Mexico poor priest-ridden Mexico will have just cause to laugh at us. The war seems to be degenerating into a systematic practice of pillage & devastation to end perhaps in one of vengeance & retaliation12
In my last excursion of about 25 sp. of shells collected in a season unfavorable 8 are new species
I examined again our little Spiranthes.13 From the flowers just opened the pollinia come out best. Those of older flowers wont stick but they project far over the stigma & being powdery or at least friable it is not unlikely either that the pollen falls naturally onto the stigma or that the upper edge of it unites with the loosened pollen in some way or that minute insects crawling over it may carry some of it to the stigmatic surface. However it may be some have the pollinia removed others close up & retain them in place while all or nearly all set their fruits.
Don José14 has covered a spike of buds of the plant I first mentioned to test the matter of fertilization & see if insects are absolutely necessary to insure seed from that orchid
25th. I didnt go to the coast. Our fisher friend sent word that he had sickness in his family & couldnt leave. So I went into the hills picking up mosses Lichens &c. Got one new Rubiaceæ—a Bertiera probably. & some fruiting orchids.
26th. I have just examined an oncidium—the largest if I mistake not in the island on one scape or panicle I counted more than 200 fl. The mechanism is plain The object is that it shall not be fertilized—and it isn’t I have never seen a fr. & Don José says the same. It is common The fl. spreads wide open has no nectary & I dont know what an insect should visit it for. But suppose a bumble-bee should but his nose against the big disk it will stick there & if he raises his head a very little the anther jumps off sometimes to a distance at other times still clasps the pollinia. Do you suppose that now these pitch forward in order to hit the next stigma he runs against? Not at all. They fall back over Mr. Bumble-bee’s knowledge-box & if he goes to a thousand other flowers the pollen doesn’t reach a stigma with his good will. Let Mr Darwin explain this if he can.15
April 1. Suspecting I had drawn hasty conclusions from the above experiments, I last night extracted a large number of the pollinia & left them till this morning when they had all undergone the movement of depression showing the correctness of Mr. Darwin’s observations.16 Today I expect to dispatch this which will go to Havana tomorrow probably
Yours ever | Charles Wright
Describes the flower and mode of action of a particular orchid.
Has been examining Spiranthes and is experimenting to see whether insects are necessary for its fertilisation.
It seems that Oncidium is designed so as not to be fertilised.
Please cite as
Darwin Correspondence Project, “Letter no. 4433,” accessed on 13 February 2016, http://www.darwinproject.ac.uk/DCP-LETT-4433