Letter to Charles Darwin (1863)
My dear Sir
I had much pleasure in receiving your Letter of the 20th. As for the Strawberry I do not set much by it. I have little doubt of its seeds being fertile—"Myatts Pine" was not an alpine—And, for aught I know the Chilian sp crossed upon it might have been some remote ally. I have a plant in my warm Pits being forced—a very singular dwarf form of the Cross; and I will send you a berry when ripe, if you wish.
The Strawberry crossed with the Raspberry (of which cross I have large plants above 5 years old, has not yet flowered—It is about coeval with the above cross which has been fruiting for the bygone 3 or 4 years. Its tardiness & its wiry stalked foliage encourages the hope that it is not quite a miss. If it fruit this year I will report to you.
In this family I have made numerous attempts besides the above.—I tried to X the Potentilla with the Strawberry. I crossed, as I believed, the latter with Rubus glabratus—an Andean species, which I believe no one else has, as I raised it from seeds transmitted by Dr. Jameson of Quito. Of this cross I have several plants; but tho’ different in foliate from its female parent, I can see little of the male parent, the rubus glabratus, which is a very dwarf bramble with deep dark shining foliage. Here I was at much pains to prevent self fertilization, by carefully opening and cutting off the male organs of the flower ere the pollen passes from it green,—unripe condition. And, as this tube is much infested by an insect of the bee family a rapacious eater of pollen I invariably pot my plants under experiment, remove them to the Greenhouse,—& farther admit no other flower on the same plant from which pollen might be transported.—Yet with all my care I may have been thwarted by some of these pests, whom the better to beguile, I invariably dismantle the bloom of the flower operated on by cutting away the corolla.
The Blackberry & Raspberry I have strong hopes of. I tried it early last year at Woodend, my place in Perthshire, putting gauze over the blooms, the Raspy plant acted on being in the open garden, but birds interfered with some, and when I returned after a 7 or 8 Weeks absence on the Continent, I found only one fruit & but with one seed partially ripe, which I sowed but which has never yet sprung. I do not know if you have found, or whether you have tried these severe crosses & found, like me, that tho you get ripe seeds you can’t get them to vegetate. The instance I am now to notice bears upon a question you put to me about the Short anthers.
About the month of March 1851 I crossed—I should rather say hybridized, if not muled the Rhodothamnus Chamaecistus with pollen of a large species of Rhododendron I had from M. Van Houtte, which, as it resembled, I named "R. Nilaghericum" which, however, it was not. I find from my Garden book for that year, the following entry under date "May 10 1851—Rhod. Chamaecistus. Counted 7 pods all finely set with seed—(pods size of sweet peas—all (save one) marked Castrate, and all crosses with my R. Nilaghericum—Short stamens" I had also crossed the same R. Chamaecistus with R. glaucum (a find dwarf Rhod n. One of Dr Hookers Sikkim sps) at the same time with the above; and the memorandum goes on. Or again looking at this mem. I find I have written R. glaucum for "K. glauca"—ie Kalmia glauca, with which the cross was attempted & not with Rhod glaucum as I had erroneously read & have here written. "Those cast and done with K glauca (blue silk) appear to have failed, a certain proof of the others being true"—The seeds of Rhodothamnus Chamaecistus from the cross with the large Rhod n., called by me R Nilaghericum) a white flowered Indian species came to full maturity. But tho I sowed them & watched them for years they never vegetated—not one of them. Now there was a very improbable looking effected by the short anthers of a large Rhododendron, having large white flowers, fully as large as those of R. cinnamomeum—on this heath like Rhodothamnus—effected at least to the point of producing seed beautifully ripened, but which proved abortive. The seeds I remember were so ripened that, as is the case with seeds of R. Chamaecistus, they were quite round and ran along paper like small shot infinitely less of course.
I had attempted the same cross in the month of March in the immediately previous year 1850—and I have noticed this in an article I wrote for "The Book of the Garden vol. II, p 319 and which Dr Lindley has done me the honour to cite, and to give at considerable length in "The Theory & Practice of Horticulture" (vid 2d Ed n. p. 490) These seeds too failed to vegetate. I find I have first noticed the capability of working with these short stamens by the following Mem under date "27 April 1850 & May 9th" Discovered that the Short stamens of Rhod n. Cinnamomeum (allied to R arboreum) & and particularly of R Catawbiense—crossed the small Rhodoth. Chamaecistus—which appear now (11 May) to be fully fertilized & pods swelling—the operation having been performed about the 27 April and castn. performed. See also operation on Azalea Phoenicea by Short Stamens of R. Cinnamomeum. Tried also on Menziesia but failed". I find another Mem of May 1850 which refers to the cross in the article given by Dr Lindley. "The first (cross) on my own old (separate Plant) of R Chamaecistus by R. Nilaghericum (so called by me) now well on to ripening performed about 5 March, supposed to have been done with Short stamens" Again, of same date, I notice a cross on the same R. Chamaecistus by Azalea procumbens which "appears to hold". But I forget what came of this—a failure probably. I find that I tried the same R Chamaecistus with Erica Odororosea which I note "appears also to hold".
These operations are somewhat akin to the one effected by Mr Cunningham of Comely bank Nursery here, by which he produced between the Menziesea (some say M Caerulea some M Empetriformis) and the same R Chamaecistus,—the Bryanthus erectus. Mr C. rather imposed on Dr Graham by this hybrid and was not fond of admitting it to be a hybrid at all while Dr G. lived—He did so to me however, for happening to be in his nursery he showed me the plant under a hand glass—and asked me, as he had done Dr G, to say what it was—And as I had been myself at work before on a Cross between the same parents—I at once guessed it to be a hybrid between the M Caerulea & R Chamaecistus when he owned I was not far off it. I found out afterwards that he had made the Menziesia the seed bearer, while I had failed, from making it the male parent. I returned to the experiment and made it on the Menziesea Caerulea (Mr C’s experiment must have been on M empetriformis) I succeeded fully & sowed the ripened seeds on 18 June 1850 and had 4 young plants through on 10 Septr. Same year. These were afterwards destroyed most ignobly by a marauding snail—So, if we make crosses we must learn to bear them—a lesson I am often taught and am now smarting under from this morning discovering that perhaps the only plant of Eccremocarpus longifolus in Europe, which after some 6 months waiting for had sprung with me, is devoured root & branch if I may so speak of a thing in its seed leaves, by some wretched grub, even tho I had covered up with glass. I saw it yesterday & today it is non est.
But of these short stamens:—from the above results I took a fancy to them, believing their pollen to have more activity in it—or at least to be better adapted, from its supposed smaller granules, for fertilizing Congeners of a lesser growth. Please observe my whole working with them was among the Rhodn. family whose flowers are alike in form & similar in having almost invariably 2 short stamens,—with the Pelargonia, I entertained the firm belief also that as they were themselves of miniature dimensions, they would be likely to produce a dwarfish progeny
The magnificent scented Rhod n. Edgworthii, (of Hooker fil.) with foliage of a distinct case from all other species fascinated everyone. But it had one great drawback being "leggy" to an undue degree. I set to work upon it, making it the male parent and effected various crosses with its pollen on R. Ciliatum a Dwarf sikkim sp., using the short stamens. Now as noticed in article in the Cottage Gardener, I got a brood of dwarfs some of which I yet have not 2 inches high. I believe these to be the progeny of the Short anthers—and have determined on watching it better ere saying aught about it, when Donald Beaton drew me out by some remarks I sent the same publication as confirmation of a like observation made by him on the Pelargoniae tribes. But it is right to observe that I at first wrought with long & short anthers from getting pollen from friends who were before me in blooming R Edgworthii. But I know when I could get them I wrought with Short & Shorter stamens as I could get them in preference to the longest ones. Your expressed doubt however of our friend Donalds accuracy demands a precise testing of the thing afresh. And I will try it: But the sad sad thing is, "life is too short for the Experiment among my favourite Rhodn. tribes—but the Pelargonium family may be tried.
I fear I am trying your patience sadly in giving you a bundle of chaff to look over for the one or two grains you may be in quest of in this absurdly too long Letter—But I must digress again by mentioning a fact in regard to crossing which I found invariable with all I tried upon R. Edgworthii that while its pollen would readily fertilise several (not all of its congeners) I could never effect one cross on it by foreign pollen. I have found this in many plants. I noticed above the same result where Rhodothamnus Chamaecistus was made the female to Menziesia—(now Phyllodoce) Caerulea while inverted the cross held & produced seeds which vegetated. But I find I must refer you to the Book of the Garden Vol II p 320 for this Experiment, for Dr. Lindley does not quote my entire article—. I find my article there, is given at length in the 26th Vol (for 1858) of Harrisons Floricultural Cabinet p 60. My ideas then ran after Lamarck. But I have been so often baffled in attempts, where I expected success as inevitable, that I have been forced to give up a great part of that bewitching theory. Yet there are times & seasons & influences which I have effected crosses I would have attempted in vain at other times & diverse circumstances. Have you considered this?—But here I am repeating myself in the Article referred to — & must now forbear to tire you longer.
To return. I will most gladly try my hands on the pelargoniums both for the above experiment of the Short anthers—and to test the fertility of the Central flower, peloria, of that tribe. In all my crosses I invariably avoided that central flower, just from the impression I had of its infertility.
I shall be delighted to receive your article on the Linums. They are a most anomalous tribe; but I have no doubt you will throw new light upon it. I will cheerfully try the experiment you point at and report the result. What I meant by L rubrum is the same which you with equal correctness name L grandiflorum. I believe the true name is L rubrum grandiflorum—an annual, and the only crimsom sp. I know of in the family
You asked me if I have any quite sterile hybrid with a rather large stigma. I know of none nearer your mark than Mr Cunninghams mule the above Bryanthus erectus, which I am sorry I have lost; but it will be found in almost every Nursery. It is a thing of high interest. I have a singular hybrid—which I have kept for nearly 10 years—it is between Phlox subulata (if that be a true Phlox)—a thing with awl shaped or grass like foliage, and P. verna a broad leaved dwarf species, with rose coloured flowers. It flowered one year & bore no seed, the bloom had all the appearance of sterility—& so far as I remember had its sexual organs imperfect. I have various things coming on which, if true, will put fertility to its severest test of this again.