29, 1882.] 



. KNOAVLEDGE 



289 



MONKSHOOD. 



By Grant Allen. 



1^0 look at these queer, irregular blue flowers, growing 

 on a long and handsome spike in the old-fashioned 

 garden border, nobody would ever dream of saying that 

 they were in reality altered and modified buttercups. And 

 yet that is just what they really are, with all the marks of 

 their cui-ious pedigree still clearly impressed upon their 

 veiy forin. Pull one of the blue blossoms off, and pick it 

 carefully to pieces, and you will see how strangely and 

 profoundly it has been distorted by insect selection. 

 Monkshood is most essentially a bee-flower, and in ex- 

 amining it we see the results of bee action plainly set forth 

 in every organ. If we pick a common meadow buttercup 

 for comparison with it, we shall be able to see exactly 

 wherein the two flowers difler, as well as why the one has 

 gained an advantage in the struggle for existence over the 

 other. 



The outside whorl of the buttercup consists, of course, 

 of five separate greenish sepals, which together make up 

 its calyx. Inside the sepals come the five golden petals 

 composing the cup-shaped corolla ; and inside the petals, 

 again, come the numerous stamens, and the equally nume- 

 rous carpels or unripe fruits, each containing a single, 

 Eolitai-y little seed. Moreover, all these parts are regularly 

 and symmetrically arranged round a common centre, so as 

 to form a series of concentric whorls. But when we look 

 at the ^monkshood, we see no such simple and orderly 

 arrangement in its architectural plan. At first sight, we 

 recognise no distinct sepals or petals ; and the coloured 

 organs that take their place are very irregular in 

 shape, and disposed in an unsymmetrical fashion — or 

 rather, to speak more correctly, their symmetry is not 

 radial, but bilateral. When we begin to pull our blue 

 blossom to pieces, however, we gradually recognise the 

 various parts of which it is composed. First of all come 

 five sepals, not greenish as in the buttercup, but bright 

 blue ; and not all alike, but specially modified to fulfil 

 their separate functions. The uppermost sepal of all is 

 helmet-shaped, and it forms the curious cowl which gained 

 the plant its suggestive name from our medieval ancestors. 

 The two side sepals, to right and left, are flatter and 

 straighter, but very broad, while the two lowest of all are 

 comparatively small and narrow. The whole five are 

 bright blue in colour. Pull off these petal-like sepals, 

 and you come to the real petals beneath them. At 

 first you can liardly find them at all ; you see only 

 two long blue horns, covert d till now by the helmet- 

 shaped upper sepal or cowl, and each with a queer cup- 

 like sac at its extremity, containing a small drop of 

 clear fluid. That fluid is honey, but T should advise you 

 to be careful in tasting it not to bite ofl' any of the flower, 

 for monkshood is the plant from which we get the now 

 famous poison, aconitine ; and a very little of it goes 

 a long way. Unlike as they are to the familiar yellow 

 petals of the buttercup, one can still gather from their 

 position that the two long hnms are really petals. But 

 where are the three others 1 Well, you must look rather 

 close to find them, and perhajis even then you won't suc- 

 ceed after all ; for sometimes the three lower petals have 

 disappeared altogether, being suppressed by the plant, as 

 of no further use to it. In this particular specimen, how- 

 over, they still survive as mere relics or rudiments, three 

 little narrow blue blades, not nearly as big as a gnat's 

 wing, placed alternately to the lower sepals. As for the 

 stamens, they are still present about as numerously as in 

 the buttercup ; whereas the carpels, or fruit-pieces, are 

 reduced to three only, which in the ripe seed-vessels here 



on the lower and older part of the spike grow into long 

 pods or follicles, each containing several seeds. 



Thus, then, the flower of monkshood agrees fundamen- 

 tally with the flower of the buttercup ; while, at the same 

 time, it has undergone some very singular and suggesti\e 

 modifications. In both there are five sepals ; but in the 

 buttercup all five are alike, and all five are greenish; 

 whereas in the monkshood they have acquired diflx-rent 

 shapes, exactly fitting them to the bee's body, and they 

 have become blue, because blue is the favourite colour of 

 bees. Again, in both there are five petals ; but in the 

 buttercup all five are similar and yellow, and all five secrete 

 a drop of honey at the base ; whereas in the monkshood 

 two of them have become long and narrow specialised 

 nectaries, while the other three, being no longer needed, 

 have grown obsolete or nearly so. Once more, the stamens 

 remain the same ; but the carpels have been immensely 

 reduced in number, at the same time that the complement 

 of seeds in each has been greatly increased by way of 

 compensation. 



Well, how are we to account for these peculiar modifica- 

 tions 1 Entirely by the action of the fertilising bees. The 

 secret of the monkshood depends, in the first place, upon 

 the fact that its flowers are clustered into a spike, instead 

 of growing in solitary isolation at the end of the stem, as 

 in the common buttercups. Xow Sir. Herbert Spencer has 

 pointed out that solitary terminal flowers are always 

 radially symmetrical, and never one-sided, because the con- 

 ditions are the same all round, and the visiting insects can 

 light upon them equally from every side. But flowers 

 which grow sideways from a spike are very apt to become 

 bilaterally symmetrical ; mdeed, whenever they are not so, 

 one can always give an easy explanation of their de\-iation 

 from the rule. Proljably the blossoms of the monkshood 

 began by arranging themselves in a long and handsome 

 spike, so as more readily to attract the eyes of insects ; 

 and that was the real starting point of all their 

 subsequent modifications. Or, to put the same thing 

 more literally, those monkshoods which happened 

 to grow spike-wise succeeded best in attracting the 

 bees, and therefore were most often fertilised in the 

 proper manner. Next, v\e may suppose, the large green 

 sepals, being much exposed to view, began to acquire a 

 blueish tinge, as all the upper parts of highly developed 

 plants are apt to do ; and the bluer they became, the more 

 conspicuous they looked, and therefore the better they got 

 on in competition with their neighbours, especially since 

 bees are particularly fond of blue. As each bee would 

 necessarily light on the middle or lower portion of the 

 flower, he would begin by extracting the honey from the 

 two upper petals ; but it would be rather awkward for him 

 to turn round, head downward, and suck tlie nectaries of 

 the three bottom ones. Hence, in course of time, 

 especially after the flower began to acquire its present 

 shape, the two top petals became specialised as nectaries, 

 while the three lower ones gradually atrophied, smce 

 the coloured sepals had practically usurped their attractive 

 function. Cut as the flower can only succeed by being 

 fei'tilised, all this-e changes must have been really subordi- 

 nate to the great change which was simultaneously going on 

 in the mechanism for ensuring fertilisation. Slowly the 

 blossoms altered to the bilateral shape — they adapted them- 

 selves by the bee's unconscious selection to the insect's 

 form. The uppermost sepal grew into the hood, so 

 arranged that the bee must get under it in order to reach 

 the lung nectaries containing their copious store of honey. 

 At the same time the bee mut-t brush against the stamens, 

 and cover his breast with a stock of adhesive pollen- 

 grains. When he flies away to the next flower he carries the 



