From J. D. Hooker 5 April 1844
West Park Kew
April 5. 1844.
My dear Darwin
Your queries & remarks have opened a wide field for research & investigation, for which I am truly obliged. These are all subjects which I ought to have attended to, without requiring to be reminded of them, by a more industrious Naturalist: truly I ought to have been able to answer you on the spot, if I had been half a Botanist, but I seem to know less every month than I did the month before as I find how much there is yet to learn—
I believe there is to a certain extent a “great relation between the ranges of Genera & individual species” Thus in the genus Linum (flax) several species are very common over all Europe, another (monogynum) abundant over the greater part of Australia & New Zealand.—a third (saginoides) has a wide range in Chili & Bonaria:1 —one or two very common over the Cape district:—L rigidum has an immense range in U. States.—L angustifolium over Europe & Asia.—& I think another species over the Brazils.— Again in the genus Drosera.—D. uniflora has a wide range over Southern Chili Fuegia & Falklands D. anglica over all middle & N. Europe—several species over a great part of Australia & V. D L.—2 D. cistiflora has (I believe) a very wide cape range, & two U.S. species an immense N. American. I think I could quote 50 instances similar to that of the two above large Genera, & plenty more striking— The contrary may however be as often true, but Negative evidence is always more difficult to find than positive; in looking for exceptions one is lost in a sea of doubt & does not know which way to look for what he wants, but when one is asked whether such a thing holds good the mind is immediately led to similar instances & corroborative evidence.— Now, though these large genera have each individual species with wide ranges, I believe they possess equally species which are remarkably local, (which however may mean no more than that the said local species have not been properly looked for). The Genus Araucaria is widely distributed, having representatives in Chili where the species cannot be said to have a very wide range, another in Brazil certainly of contracted limits—2 very sparingly indeed distributed in Australia, & a 4th confined? to Norfolk Island.. Again some Genera of only single species have a mundane range, & others of but few are widely distributed, each species in its region; thus Trientalis Europæa is abundant all over North Europe & T. Americana over all Northern America. Few plants are however really so rare & so confined as many animals, from not having so many enemies.
On the whole I believe that many individual representative species of large genera have wide ranges, but I do not consider the fact as one of great value, because the proportion of such species having a wide range is not large compared with other representative species of the same genus whose limits are confined—& further because small genera have likewise individual widely extended representative species. The converse holds true in a certain degree & in the Cacti we have a parallel case to Monkeys, their geographical range is small being confined to warm & chiefly to tropical S. America & Mexico I have somewhere read that the species are remarkably peculiar to certain narrow limits. My Father (who I just asked) confirms this & adds that they are most remarkably local as species & equally so as genera, the Turks’ Caps are chiefly confined to the W. Ind. Islands those with ribbed spines to Mexico &c & C. triangularis common to all tropical S. Am. is supposed to have been introduced.— The same holds good with the S. African Stapelias,—with the Nat. Ord. Rafflesiaceæ, with many peculiar Australian genera &c. I believe the rule is very good that “the Individual species of local genera are themselves local” as also that “In mundane genera many of the species have mundane ranges”, but that it is not proved in Botany that “in mundane genera the representative species have a wide range each in its own country”, to any remarkable extent. What you say of Junci is very true that they form a mundane Genus & many of the species have extended ranges but I do not know that it is the representative species that have wide ranges each in its own territory, even if true I would answer that water plants (as many are) are more widely diffused than dry land species— To conclude, I believe that most large mundane Genera contain both 1 st many different species each with restricted limits, & 2 nd also a large proportion of species with very wide ranges besides 3 rd many local species with very narrow ranges: but it is not apparent that the proportional number of species distributed under any one of these conditions is larger in general than those distributed under either of the others.— I shall however bear the matter in mind & hope for new lights in time.. 3
With regard to typical genera having wide ranges Swainson is an instance of the type of a certain class of Naturalists wandering very far indeed both mentally & bodily. I hardly know what is always meant by a typical form. The character of a group should be founded on the most important objects it contains in the œconomy of nature. The most important genus of a class is surely generally either the largest or the most widely diffused; if the largest genus is the type, we have already seen that large genera are generally most widely diffused. The type of a group often turns out (on extended knowledge of that group) to be the most aberrant form in it.— Perhaps Swainson has put the cart before the horse & should have said “a typical group or genus is that which is the most widely diffused”—4 Some however I think define typical forms as those which are most fully developed or what they call most perfect, now though it may be very easy in any group to point out many which are not the most perfect or fully developed, a great many remain amongst which it is difficult to say which has the advantage of the other in organization.— I suppose you are acquainted with Mc Leays writings, if his views are to be followed out all our theories must be 5 capsized as he leaves us nothing but the remnants of an Animal Kingdom to work upon.6 Have you paid any attention to his circular & Quinary system?…7 I cannot call this long prosy letter an answer to yours, I feel that I have given nothing but vague & unsatisfactory information; another time, ere long, I shall hope to have some naked facts sought out, bearing directly on the grand question, “Have the 10 representative individual species of widely distributed genera over 10 countries wide ranges each in its country.”?— I think I state it as you wish it answered.
Smith & Elder gave the greatest & kindest attention to my book but I think the outlay required frightened them, as we wanted £1. on each plate to get them done in soft ground lithograph, which cannot be done at the Govt grant of £2 a plate, I also asked a share of the profits; an idea long abandoned; Every publisher was equally alarmed at the extent of the work &c except Mr Lovell Reeve of King Wm Street Strand, who, keeping his own lithog. press, works very cheaply. I give him all materials & plates on stone for a few copies of the work— it will be produced at 1/ a plate cold ; including letterpress, the same price as Belcher’s Botany uncolored,8 & 7d a plate uncold.. I should have liked Smith & Elder better than any; but they did not seem to like so very extended a work, & further, to tell you the truth your estimates are so very much higher for printing &c that they do not seem to have gone so economically to work as they might have consistently with good execution—.— I have worked the Galapago Isld plants up to Compositæ & am now writing out clean the first part for printing
You must find planting a great recreation, I wish you would come to Kew & see the plans for planting 48 acres as an Arboretum. I wish I could send you a list of the depths at which we obtained live Corals—off New Zealand we dredged live Hornera frondosa from 400 fathoms.. 9
Believe me Yours most truly | Jos D Hooker
We have live Fagus Antarctica & Forsteri at Kew, old friends!—. also Berberis ilicifolia & Winters bark all from our voyage
Answer to CD’s query on genera and species ranges.
Comments on typical forms.
Preparing first part of Galapagos plants for printing.
Please cite as
Darwin Correspondence Project, “Letter no. 745,” accessed on 1 October 2016, http://www.darwinproject.ac.uk/DCP-LETT-745