June 30,1900, 
THE GARDENING WORLD 
695 
AQUATIC PLANTS. 
At the Drill Hall meeting held on the 19th, inst., 
Prof. Boulger lectured on " Aquatic Plants.” He 
treated the subject entirely in the scientific aspect, 
but to those who were able to follow his discourse, 
the lecture was very interesting. 
Gardeners classified plants, said the Professor in 
his opening remarks, according to their partiality 
for a warm, an intermediate, or a cool temperature. 
And epiphytic Orchids, as another example, were 
usually subjected to quite different treatment to 
that of terrestrial ones. The gardener therefore ran 
on the lines of the physiologist rather than those 
of the anatomist. In early times botanists merely 
grouped vegetation roughly into groups, as trees, 
shrubs, herbs, according to their various medicinal 
properties. Later a single set of characters was 
considered, such as the reproduction organs upon 
which the artificial system of Linnaeus was en¬ 
tirely founded. But more was wanted. It was 
Darwin who first showed that affinity meant 
relationship. Characters possessed in common by 
large numbers of plants seemed to be derived from 
remote ancestors. From these characters, botanists 
have been able to build up the great primary di¬ 
visions of the natural system of classification. 
What these characters were in the Angiosperms, 
Gymnosperms, and Cryptogams the lecturer briefly 
described. 
The characters belonging to species may be 
divided into those which are inherited, and those 
which are acquired. Mere physiological characters 
are no guide, but these and a study of the repro¬ 
ductive organs form a guiding system. Referring 
strictly to aquatic plants, Prof. Boulger delineated 
the distribution of some of the better known genera. 
So widely scattered are some of the genera, that 
only the species can be called local. A point of 
interest here noticed was that in temperate regions 
hibernation during winter becomes essential.Marsilea 
and Subularia were genera referred to in this 
connection. The Water Star Wart and some others, 
however, remain unaltered. The species of Apono- 
geton on the other hand are like the above mentioned, 
the Marsilea, &c., in that they die down to the 
rhizomes, like any other common terrestrial her¬ 
baceous plant. Another large group of aquatics 
form buds of modified leaves before they die back in 
autumn. The common English Arrowhead 
(Sagitfaria) and the Frogbit are examples. These 
buds fall to the muddy bottom, and there they lie 
till their dormant capacities are awakened by some 
power or other in spring and they begin to develop 
a new plant unit. When flowering is over and 
growth well developed in autumn, the young bud- 
plants are seen at the end of long shoots, like a 
Strawberry with runners, or a Houseleek with oflsets. 
By and bye the base of the stalks rot, the "hen 
and her chickens" become separated, and the 
"buds” sink to the bottom. And so the cycle 
goes on. 
The power of certain aquatics (e g. Elodea cana¬ 
densis) to spread and propagate vegetatively received 
note. This Canadian Weed, named above, was in¬ 
troduced to Britain in 1836, and though only male 
plants were ever discovered here, in a few years it 
became an unmitigated nuisance to farmers, gar¬ 
deners and others, for by its vigour, streams and 
ditches were completely chocked with it. But once 
the soil lost its virgin quality, the Elodea also 
lessened in its vitality. 
The foliage of entirely submerged aquatics is 
excessively thin. Aquatics usually have two or more 
forms of foliage leaves, which vary in consistency, 
&C., as submerged leaves, floating leaves, or leaves 
raised erect. The fineness or degree of dissectedness 
to which an aquatic's leaves may become modified, 
has been statistically accounted as varying in pro¬ 
portion to the swiftness or moving rate of the water 
in which they grow. The swifter the stream, the 
finer the leaves. Vallisneria spiralis and species 
of Callitriche are subjects which demonstrate this 
fact. The length, compared with the breadth, of 
submerged leaves is remarkable. They are usually 
very much longer than they are broad, being so 
much as thirty times as long as broad, in Hippuris. 
It seems odd to be told that the roots of aquatics are 
principally useful for anchorage. Prof. Boulger 
dealt minutely with the histological and physiological 
characters of a few particular species, contrasting 
them, and showing their points of likeness or differ¬ 
ence. Modified leaf-hairs serving as roots are seen 
in the Water Chestnut, and in Salvinia. It is worth 
noticing that Castalia is now the botanically accepted 
name of the White Water Lily, in place of Nym- 
phaea. 
The quantities of certain saline ingredients which 
such aquatics as Juncus bufonius, Isoetes, Villarsia, 
&c. take in, is surprising. It is also known that 
these surplus quantities are not essential for their 
regular growth. For instance, on analysis the ash 
of a Duckweed gave 7J per cent, of iron ; while in 
the Water Chestnut in the plant there was 29^ per 
cent, of iron, and as much as 68J per cent, in the 
fruit. 
The bladder cells on the leaves of some aquatics, 
are primarily useful as " floats,” but they also aid 
in the assimilation of oxygen. In Utricularia, the 
objects that used to be thought of as floats are really 
" traps ” for the catching of insects. Air-cavities or 
air-tissues are developed enormously in some genera, 
and the “ Knees ” formed upon the roots of the 
Deciduous Cypress (Taxodium distichum) are a case 
in point. So numerous are air spaces in aquatics, 
that when they are cut and exposed to the free air 
they very speedily collapse. In running water again, 
floats and air-spaces cease to be developed ( e. g. the 
Water Crowfoot). The concluding remarks applied 
to the origin of aquatics. The low forms of Algae 
are the primary and simplest constructed types. 
They are sexually reproduced by means of male 
fertilising antherozoids which are liberated generally 
in the water. True flowering aquatics on the other 
hand very seldom burst their pollen-cases under 
water (about fifty species do), and they may be 
simply instances of adaptation to environment and 
circumstances. 
PLANTS RECENTLY CERTIFICATED. 
Awards made by the Royal Horticultural Society, 
on the 19th inst. 
Orchid Committee. 
Odontoglossum Rolfeae Walton Grange var. 
—This is considered the best of all the supposed 
natural hybrids between O. harryanum and O. 
Pescatorei. The oblong sepals are rich brownish- 
purple, transversely barred with white, while the tip 
is rosy-purple. The petals are ovate, straight, 
revolute at the tip, rich brownish-purple and netted 
with white. The large lip is nearly square, with a 
large, crescent-shaped [blotch of rich chocolate in 
front of the crest, and spotted at the sides, while the 
upper third is white. (First-class Certificate.) W. 
Thompson, Esq. (gardener, Mr. W. Stevens), Wal¬ 
ton Grange, Stone, Staffs. 
Sobralia Veitchi aurea. —The typical S. 
Veitchi has flowers of the palest blush-white and a 
yellow throat. The variety under notice is 
characterised by the yellow of the throat being 
carried all over the flower, making it a handsome 
acquisition. (Award of Merit.) Sir Frederick 
Wigan, Bart, (grower, Mr. W. H. Young), Clare 
Lawn, East Sheen. 
Floral Committee. 
Iris paradoxa —The falls of this peculiar form 
of Iris belonging to the section Onocyclus, are short, 
oblong, velvety and almost black. The standards 
are very much larger, obovate, white and striated 
with slender, violet lines. The stigmas are recurved 
and brown. (First-class Certificate.) C. G. Van 
Tubergen, Jun., Haarlem, Holland. 
Iris urmiense. —In this we have another species 
belonging to the Onocyclus group of Irises. The 
leaves are linear, leathery, and glaucous. The scape 
is about 6 in. high, and bears a solitary primrose- 
yellow flower, with a deeper yellow blotch on the 
centre of the falls. (Award of Merit.) C. G. van 
Tubergen, Junr. 
Campanula persicifolia Moerheimei. — The 
flowers of this double variety are very large, pure 
white, and consist of about three corollas, placed one 
within the other, in the form of a large basin. They 
are very much larger than the fine old double form 
named C. p. coronaria, though not so fully double. 
They bear the same relation to the latter which the 
modern so called double Delphiniums and double 
zonal Pelargoniums do to the old types of thirty 
years ago. (Award of Merit.) Messrs. T. S. Ware, 
Ltd., Hale Farm Nurseries, Feltham, London. 
Anchusa italica grandiflora. —The rich blue 
and handsome flowers of this variety are very much 
larger than those of the type, and therefore an 
acquisition. (Award of Merit.) Mrs. Bulteel, 
Sefton Park, Slough. 
Delphinium Queen of Huish. —The flowering 
panicle of this variety is conical, and bears large 
flowers of a rich and handsome dark blue. (Award 
of Merit.) Messrs. Kelway & Son, Langport, 
Somerset. 
Paeonia Eastern Queen. —This interesting and 
handsome Paeony has two or three rows of broad, 
outer petals of a rich crimson-red, surrounding a 
central mass of narrow, petaloid stamens, partly red 
and partly yellow. (Award of Merit.) Messrs. R. 
Wallace & Co., Kilnfield Gardens, Colchester. 
Heuchera micrantha rosea. —Very graceful are 
the panicles of small flowers of H. micrantha, either 
on the rockery or amongst cut flowers. The variety 
differs from it in having bright red instead of brown 
stems. (Award of Merit.) Messrs. R. Wallace & 
Co. 
Iris Germanica Black Prince.— The falls of this 
variety are of a velvety violet-black, with a yellow 
beard. The standards are blue. The variety is a 
very distinct one. (Award of Merit.) Mr. Amos 
Perry, Hardy Plant Farm, Winchmore Hill, 
London. 
Geranium sanguineum album. —The diffuse 
stems and small, fine cut leaves of the typical G. 
sanguineum make it a useful rock plant. The 
variety differs in having pure white flowers. (Award 
of Merit.) Mr. Amos Perry. 
Eremurus Warei —The spike shown by Messrs. 
T. S. Ware, Ltd., was of medium vigour and closely 
covered with bright yellow flowers, darker than 
those of E. Olgae, which may be one of its parents, 
as it is suspected to be a natural hybrid. Messrs. T. 
S. Ware describe it as a new species from Central 
Asia, and state that it usually grows 8 ft. high. It 
is certainly very handsome. (Award of Merit.) 
- - 
The Orcliid Browers’ Calendar. 
Potting Orchids. —I can well remember the time 
when to advise the repotting of any Orchids during 
the summer months would have brought forth a 
storm of ridicule from most of the recognised author¬ 
ities or writers on this beautiful class of plants, but 
happily all this is altered, the consequence being we 
get much better results all round; for there is no 
question that to do potting at stated periods, 
whether the plants are ready or not, is as great a 
mistake as it is to miss the flowing tide. 
You must in a great measure do as the plants 
dictate I have often pointed out that it Is a golden 
rule to catch the plants just as they are pushing new 
roots from the newly made up growths, for afford¬ 
ing some new material. 
Generally those that have missed flowering are 
the first to make new roots and must necessarily be 
seen to first; leaviag those that are flowering un¬ 
disturbed until that satisfactory period has passed, 
except to give them a few fresh lumps of peat for 
the new roots to take hold of, which may of course 
be left intact when the potting is done. 
I have in my mind's eye just at present the 
beautiful, but alas, shy flowering Cattleya Gigas, of 
which we grow a quantity and which will receive 
immediate attention. Plants of Cattleya Mendelii 
that have gone out of flower will be potted at once, 
as will any other Cattleyas or Laelias that seem 
to ask for it. 
Odontoglossums. —We are always having some 
or other of this species on the potting bench to over¬ 
haul ; and unless you do this you cannot keep the 
collection in good condition for long. 
A Substitute Wanted for Peat. —The general 
cry is that the peat besides being too high in price is 
becoming smaller by degrees and beautifully less, as 
the saying goes. We have had Polypodium fibre 
and found it wanting after a good trial, especially 
when used for hot things. The fact is it is too 
spongy, and will not let the water pass away freely. 
I believe it is still largely used on the Continent for 
Odontoglossums, with a little leaf mould and sand 
well mixed together, with of course some sphagnum 
moss. We have not tried it ourselves, but turning 
out some recently bought in plants from across the 
silver streak, we were much impressed by the fine 
healthy root action, where partially decayed leaves 
were used.— S.C. 
