366 
t Ootober S7, 1887. 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
for fertilisation. Amongst foreign plants now common in conservatories, 
Clerodendron Thompsoni, a verbenaceous African climber, is a good 
example of a proterandrous plant. Its crimson corolla and bright 
white calyx in combination are very conspicuous and serve to attract 
insects. The long filiform filaments and style, upwardly enrolled in 
the bud, straighten and project when the corolla opens, the stamens 
remain straight, but the style proceeds to curve downward and backward 
on the second day, the anthers are effete, and the filaments recurved and 
rolled up spirally ; while the style has taken the place of the filaments, 
and the two stigmas, now separated and receptive, are in the very 
position occupied by the anthers the previous day. The entrance by 
which the proboscis of a butterfly may reach the nectar at the bottom 
is at the upper side of the orifice. It is impossible for the flower to 
self-fertilise. A good sized insect flying from flower to flower, and plant 
to plant, must carry pollen from one to the stigma of the other. 
I cannot help calling attention to the mode in which cross-fertili¬ 
sation is secured in the Blue Meadow Crane’s Bill (Geranium pratense) 
for several reasons. This beautiful Crane’s Bill, with its lovely blue 
corolla and elegant leaves, must be well-known to all who stroll in 
the meadows adjoining the Avon or by the brooks in the neighbourhood 
of this fair city. It is especially interesting as the flower which first led 
Sprengel to his researches. “ In the year 1787,” writes Sir John Lubbock, 
“ he (Sprengel) observed that in the corolla of this species there are a 
number of delicate hairs, and convinced, as he says, ‘ that the wise 
Author of Nature would not have created a single hair in vain,’ he 
endeavoured to ascertain the use of these hairs and satisfied himself 
that they served to protect the honey from rain.” Another point of 
interest in this flower is the spontaneous movement of the stamens and 
pistils. Kolreuter seems to have been the first to observe this motion in 
another dichogamous plant, Ruta graveolens. He supposed that the 
object was to bring the stamen in contact with the pistil and so insure 
close fertilisation. Nature, as Sprengel pointed out, had'a very different 
purpose to fulfil. It was to bring the stamen and pistil successively in 
contact with the same part of the insect’s body, and so insure cross- 
fertilisation. When the flower first op ns, the stamens lie on the petals, 
at right angles with the upright pistils. As they come to maturity they 
raise themselves parallel, and close to the pistil, which is, however, not 
yet capable of fertilisation. After they have shed their pollen they 
return to their original position and the stigmas unfurl themselves. As 
the stigmas do not become mature until all the stamens have shed their 
pollen, G. pratense is wholly dependent upon insect aid for fertilisation. 
The spontaneous movement thus insures cross-fertilisation, and indicates 
another of Nature’s plans for bringing about the end desired by making 
certain insects the carriers of the pollen. 
I will now direct attention to another very successful arrange¬ 
ment for promoting cross-fertilisation through the agency of insects. 
Probably many have notice 1 the Primroses (Primula vulgaris) 
present different appearances with regard to the stamens and pistils. 
In some the pistil is found at the top of the tube, and the stamens 
half way down ; in others the stamens are at the top of the tube, and 
the pistil half way down. Corresponding differences may be seen in 
the Cowslip (P. veris), Polyanthus, and Auricula. This difference in 
the form of the flowers has long been known by the homely names of 
“ thrum-eyed and pin-eyed.” Plants which present these differences of 
form are known as heteromorphus ; those which have two forms of 
flower, like the Primrose, as dimorphous; and those which have three 
forms, as in Lythrum salicaria (Purple Loosestrife), as trimorphous. 
Sprengel, as Darwin mentions, had noticed this difference in form in 
Hottonia before 1793. “Sprengel,” writes Darwin, “with his usual 
sagacity, adds that he does not believe the existence of the two forms to 
be accidental, though we cannot explain their purpose.” Trimorphism 
was noticed by Vaucher in 1811, and by Wirtgen in 1848. It was left 
to our great naturalist, Charles Darwin, to interpret, in the Journal of 
the Linnajan Society, 18C2, this curious phenomenon. 
Referring to dimorphism in the case of the Primrose, Sir John 
Lubbock observes, “ An insect thrusting its proboscis down a Primrose 
of the long-styled form, would dust its proboscis at a part which, when 
it visited a short-styled flower would come just opposite the head of the 
pistil, and could not fail to deposit some of the pollen on the stigma. 
Conversely, an insect visiting a short-styled plant would dust its pro¬ 
boscis at a part further from the top; which when the insect conse¬ 
quently visited a long-styled flower would again just conn opposite the 
head of the pistil. Hence we see by this beautiful arrangement insects 
must carry the pollen of the long-styled form to the short-styled, and 
vice versa." Mr. Darwin has shown that much more seed is set if poll n 
from the one form be placed on the pistil of the other, than if the 
flower be fertilised by poll n of the same form, even taken from a 
different plant. 
This eminent naturalist, in his interesting work on the forms of 
flowers, after giving a minute and graphic description of trimorphism 
in the case of Lythrum salicaria (Purple Loosestrife), observes, “ In a 
state of Nature the flowers are incessantly visited for their nectar by 
hive or other bees, various Diptera, and Lepidoptera. The nectar is 
secreted all round the base of the ovarium ; but a passage is formed 
along the upper and inner side of the flower by the lateral deflection of 
the basal portion of the filaments ; "so that insects invariably alight 
on the projecting stamens and pistils, and insert the proboscis along 
the upper and inner margin of the corolla. We can now see why the 
ends of the stamens with their anthers, and the end of the pistil 
with the stigma, are a little upturned; so that they may be brushed 
by the lower hairy surfaces of the insects’ bodies. The shortest 
stamens; which lie enclosed within the calyx of the long and mid* 
styled forms, can be touched only by the proboscis and narrow chin 
of a bee ; hence they have their ends more upturned, and they are 
graduated in length, so as to fall into a narrow file, sure to be raked 
by the thin, intruding proboscis. The anthers of the longer stamens 
stand laterally further apart, and are more nearly on the same level, 
for they have to brush against the whole length of the insect’s body. 
“ I have found no exception to the rule that when the stamens and 
pistil are bent, they bend on that side of the flower which secretes 
nectar. . . . When nectar is secreted on all sides, they bend to that side 
where the structure of the flower allows the easiest access to it, as in 
Lythrum. ... In each of the three forms, two sets of stamens corre- 
spond in length with the pistil in the other two forms. When bees sucls 
the flowers, the anthers of the longest stamens, bearing the green pollen, 
are rubbed against the abdomen and inner sides of the hind legs, as is 
likewise the stigma of the long-styled form. The anthers of the mid¬ 
length stamens, and the stigma of the mid-styled form, are rubbed 
against the under side of the thorax and between the front pair of legs. 
And lastly, the anthers of the shortest stamens, and the stigma of the 
short-styled form, are rubbed against the proboscis and chin ; for the 
bees in sucking the flowers insert only the front part of their heads 
into the flower. On catching bees, I observed much green pollen on 
the inner side of the hind legs, and on the abdomen, and much yellow 
pollen on the under side of the thorax. There was also pollen on the 
chin, and, it may be presumed, on the proboscis ; bat this was difficult 
to observe. I had, however, independent proof that pollen is carried on 
the proboscis ; for a small branch of a protected short-styled plant 
(which produced spontaneously only two capsules) was accidentally left 
during several days pressing against the net, and bees were seen insert¬ 
ing their proboscid s through the meshes, and, in consequence, numerous 
capsules were formed on this one small branch. ... It must not, how¬ 
ever, be supposed that the bees do not get more or less dust d all oyer 
with the several kinds of pollen ; for this could be seen to occur with 
the green pollen from the longest stamens. . . . Hence ins cts, and 
chiefly bees, act both as general carriers of pollen, and as special carrien 
of the right sort.” 
A long series of experiments proved that both kinds of pollen are 
nearly or quite impotent upon the stigma of the same flower, and that 
no ovary is fully fertilisable in any other manner than by stamens of 
the corresponding length. Nessea verticillata, a common Lythraceous 
plant of the Atlantic United States, is, according to Dr. Asa Gray, 
similarly trimorphous. Several South African and American species of 
Oxalis are trimorphous, and have been investigated by Darwin anil 
Hildebrand, with the same result as in Lythrum salicaria. Referring 
to trimorphism, Mr. Darwin observes in one of his valuable works, as 
follows : — “ Fritz Muller has seen in Brazil a large field, many acres in 
extent, covered with the red blossoms of one form (of an Oxalis) alone, 
and these did not produce a single seed. His own land is covered with 
the short-styled form of another species, and this is equally sterile ; but 
when the three forms were planted near together in his garden they 
seeded freely.” “ All known flowers,” writes Dr. Asa Gray, “ exhibiting 
reciprocal dimorphism, or trimorphism, are entomophilous ” (insect 
fertilisable). No such wind-fertilisable species is known. Few of them 
are irregular, and none very irregular ; they do not occur, for instancri 
in Leguminosas, Labiatre, Scrophulariacae, Orchidaceie, Ac. Nature is 
not prodigal, and does not endow with needless adaptations flowers 
which are otherwise provided for.—W. G. Wheatcboft (in Journal of 
Microscopy ). 
(To be continued.) 
ROYAL HORTICULTURAL SOCIETY. 
October 25th. 
A remarkable display of vegetables was provided in the conservatory 
at South Kensi gton on Tuesday last, when the numerous prizes offered by 
the Lading firms of seedsmen induced a large attendance of exhibitors. 
Very seldom is such an extensive show seen in London, as, besides the col¬ 
lections, consider ible space was occupied with Potatoes, Onions, Celery, 
and Carrots, the majority of fine quality. In addition to these there were 
the usual exhibits befor > the Floral and Fruit Committees, Messrs. Hooper 
and Co.’s Carnations and Mr. R. Gilbert’s Burghley novelties being ths 
chief features in each case. The side tables were fully occupied, and a 
broad central table, extending the whole length of the conservatory, was 
filled with the vegetables, the western half being devoted to Messrs. 
Sutton’s classes, and the opposite end to Messrs. Carters’, Webb’s, and 
Wood’s classes. 
Fruit Committee. —Present—H. J. Veitoh, Esq., in the chair, and 
Messrs. T. J. Saltmarsb, T. B. Haywood, A. H. Pearson, Harrison Weir, 
Arthur W. Sutton, C. Ross, Wm. Denning, W. Warren, R. D. Blackmore, 
J. Burnett, P. Barr, Sidney Ford, and John Woodbridge. Messrs. J. Veitch 
and Sons, Chelsea, exhibited handsome fruits of Bismarck, Sandringham, 
and Baumann’s Reinette AppLs, the latter highly coloured. Mr. C.Ross, Wel- 
ford Park Gardens, Ne vbury, was awarded a cultural commendation for three 
excee ingly fine Smooth Cayenne Pine Apples, weighing 8) lbs., 8 lbs., and 
6 lbs. 13 ozs., very deep finely proportioned fruits of a rich colour. Mr. T. 
Lrxton, Bedford, sent fruit of his seedling Pear, Laxton’s Bergamot, but it 
was over-ripe. Mr. J. Bond, Coventry, sent fruits of Adam Bede Apple. 
Messrs. James Backhouse & Son-*, The Nurseries, York, showed samples of 
Backhous ’s Beurre Pear. Mr. Hough, Harrow Hill, showed fruits of an Apple 
named Harrovian, which was passed. Mr. H. Wingrove, Rousham Park 
Gardens, Steeple Aston, Oxon, sent fruits of a pretty little yellow Apple, 
said to be a seedling from Blenheim Pippin. Messrs. W. Johnson & Son, 
Boston, Lincolnshire, exhibite i fruits of Apple Manchester Beauty, of a 
bright rei colour, and fair flavour. Mr. S. Ford, The Gardens, Leonardslee, 
