142 " THE DICTIONARY 
OF GARDENING, 
VENTILATION. Ventilation, or air-giving, is one 
of the most important operations in garden management, 
— and the cultivation of all kinds of trees and plants under 
. glass. Ventilators are requisite in“@ll horticultural struc- 
tures, for the purpose of regulating temperatures, and 
affording an interchange of air in their interiors. The 
. amount of space made available for opening to admit 
air, depends on the kind of plants cultivated in any 
particular structure, as, for instance, conservatories and 
greenhouses. Peach houses and vineries need provision 
for the admission of an abundant circulation of air 
whenever it is required, or when circumstances and 
weather permit; while in plant stoves and houses in 
which the occupants need a more or less tropical atmo- 
sphere at all times, a smaller number of ventilators 
will suffice. It is always advisable to have some plan 
of giving Ventilation at, or near, the top: this is pro- 
vided in most houses of modern construction, so that 
the least supply, or nearly the full amount, of air may 
be admitted without rain getting in, except from an 
occasional splashing. Ventilating gearing has been greatly 
improved during recent years, so that either top or bottom 
sashes along a house, say 30ft. long, may be easily opened 
or closed with one hand, working a lever, and the sashes 
may be fixed with the other hand to wherever they are 
required to remain. Where there are no side or front 
sashes, as in many lean-to houses, wooden door venti- 
lators are best, fixed in the front wall; and if the air 
from these can be made to pass over the hot-water pipes, 
it will become warmed before reaching the plants. 
Wooden ventilators may be similarly placed in a back wall; 
but wherever convenient, lifting sashes are preferable. 
There are numerous details attending the admission 
of air which depend on widely varied circumstances, 
and can only be learnt by practical experience; the state 
of the weather, which is often very changeable, and the 
difference between outside and inside temperatures, being, 
perhaps, the most important points to consider. At 
different seasons, too, the same plants will need very 
dissimilar treatment according to their stages of growth. 
During spring, the greatest care is necessary regarding 
the admission of air, as sudden changes of temperature, 
caused by improper Ventilation, quickly show their evil 
effects on young and tender foliage. In old-fashioned 
houses, with small panes of glass, the sun never has 
the same effect in raising the temperature inside, as in 
most of those of modern construction with large panes; 
hence the necessity of early attention to Ventilation 
becomes much greater with the last-named. Happily, 
many of the improved systems of applying air, as already 
referred to, afford the means of opening or closing 
the ventilators in a tenth part of the time occupied 
in handling each sash separately in a large house. In 
daily management, when it is known that air will 
have to be admitted to a house, the ventilators should 
be opened very gradually so soon as the temperature 
begins to rise in the morning or early part of the 
day. It is never good practice to allow the tem- 
perature to get high and then put on what air is 
required for the day at once, or even at twice. Under 
such management tender foliage often droops quickly 
because of a sudden change and excessive evaporation 
taking place. Few plants or trees are able to withstand 
this: their leaves often become scorched during the day, 
and the attacks of insects are much encouraged. In 
spring, the ventilating of forcing-houses and other 
structures may require somewhat different management 
nearly every day in order to keep near the requisite 
degree of heat. The quantity of air and the mode of 
applying it are, therefore, matters which must be deter- 
mined in dealing with the culture of plants under such 
varied circumstances. What may be called general ` 
advice is to begin ventilating early, as already noted, 
when it is pretty certain that airing will be necessary, 
Ventilation—continued. 
and apply a little more at frequent intervals until suffi- 
cient for the day is put on. Secondly, draughts should 
always be avoided: if the air is cold or the wind rough, 
never open ventilators at the front and back parts of a 
house at the same time, unless the occupants are such 
as take no harm—and this is seldom the case. In summer, 
when the inside and outside temperatures are much 
more uniform than at other seasons, air may generally 
be most freely admitted without causing much injury. 
VENTRAL. Belonging to the anterior or inner surfac 
of a carpel; opposed to dorsal. i e 
VENTRICOSE. Swelling unequally, or inflated on 
one side; e.g., the corolla of many labiate and personate 
plants. 
VENTRICULOSE. Abounding with veinlets. 
VENUS’ BASIN. An old name for Dipsacus syl- 
vestris. = 
VENUS’ FLY-TRAP. Se Dionea muscipula. 
` ‘VENUS’ GOLDEN APPLE. A common name fo 
Atalantia monophylla (which see). * 
VENUS' HAIR. A common name for Adiantum 
Capillus-Veneris (which see). na 
VENUS’ LOOKING-GLASS. 
Specularia Speculum (which see). 
VENUS’ NAVELWORT. See Ompk 
folia. oe ner oe 
VENUS’ OR VENICE SUMACH. 
name for Rhus Cotinus (which see). 
VEPRIS. Included under Toddalia (which see). 
VERATAXUS. A synonym of Taxus (which see). 
VERATRUM (the old Latin name, used by Lucretius 
and Pliny, from vere, truly, and ater, black; alluding to 
the colour of the root). False or White Hellebore. ORD. - 
Liliacem. A genus embracing eight or nine species of ` 
hardy, perennial herbs, inhabiting Europe, Russian Asia, - 
and North America. Flowers numerous in a terminal 
panicle, shortly pedicellate; perianth purplish, greenish, 
or whitish, persistent, broadly campanulate or explanate ; 
segments (in hermaphrodite flowers) connate towards the 
base in a very short tube, in others oblong, spreading, sub- 
equal, scarcely contracted at base, many-nerved; stamens 
six. Leaves often broad, plicate-veined, contracted in an 
ample sheath, the upper ones rarely all narrow ; floral ones 
bract-like. Stem erect, leafy. Rhizome thick (very 
poisonous), the root-fibres somewhat poisonous. The best- 
known species are here described. Gardeners make use 
of V. album, powdered, to destroy caterpillars. Vera- 
trums thrive in any rich soil. Propagation may be ` 
effected by divisions, or by seeds. ` 
V. album (white).* Langwort; $ i itish 
within, nh Gate s bue ue Tour on 
segments crisped-denticulate; pedicels very short or almost want- ` 
ing; racemes dense, the rachis pubescent; panicle lft. to 2ft. 
long. July. J. rather firm, plicate, puberulous beneath; radical 
ones oblong, lft. long, 5in. to 6in. broad. Stem puberulous, with 
= Hn Se leaves ub a CH Lied and gie 1548. 
species, are regarded, by Baker, as mere waris: . 
V. a. Lobelianum (Lobel's, perianth wholly greenish, B 
ype ; teral racemes 
A popular name for - 
segments narrower than in 
erecto-patent. 1818. 
V. a, viride (green) fl., perianth 
late, — een Da ` two three $ 
racemes loose-flowered, often reflexed. rth - America, 
SYN. Helonias viridis (B. M. 1096). Ar To an ES 
V. Maackii (Maack’s). Jl, perianth dark-purple, tin. to 
the segments oblong, blackish at base; lower Lx | 
to four lines long ; lateral racemes ding; very 
éin. to 12in. long. Summer. l., lower ones lanceolate 
greenish, the ts lanc 
jes e segments lar 
