PL A 
Wherein air is commonly received and expelled, i. e. 
inspired and expired ; within which tracheae he (hews 
all the former feries of" veffels are contained. 
Hence it follows, that the heat of a year, nay, of a 
day, of a Angle hour or minute, mult have an effedt 
on the air included in thefe trachea, i. e. muft rarefy 
it, and confequently dilate the tracheae, whence arifes 
a perpetual fpring or fource of adion to promote the 
circulation in plants. 
PLANT AGO. Tourn. Inft. R. IT. 126. tab. 48. 
Lin. Gen. Plant. 133. Plantain. To this genus Dr. 
Linnaeus has joined the Coronopus and Pfyllium of 
Tournefort. The firft: of thefe is called Hart’s-horn, 
the latter Fleawort. Of thefe there are feverai diftind 
fpecies, and lome varieties ; but as they are rarely 
cultivated in gardens, I fliall not enumerate them 
all here, and fliall only mention fuch of them as grow 
/ naturally in England. Of the Plantain there are the 
following forts ; the common broad-leaved Plantain, 
called Way bread ; the great hoary Plantain or 
Lamb’s-tortgue ; the narrow-leaved Plantain or Rib- 
wort; and the following varieties have alfo been 
found in England, which are accidental ; the Befom 
Plantain, and Rofe Plantain. The Plantains grow 
naturally in paftures in moft parts of England, and are 
frequently %Tery troublefome weeds. The common 
Plantain and Ribwort Plantain are both ufed in medi- 
cine, and are fo well known as to need no defcription. 
Of the Coronpus or BuckVhorn Plantain there are 
two varieties growing in England, viz. the common 
Buck’s-horn, which grows plentifully on heaths every 
where, and the narrow-leaved Welfh fort which is 
found upon many of the Welfh mountains. The firft 
of thefe was formerly cultivated as a fallad herb in 
gardens, but has been long banifhed from thence for 
its rank difagreeable flavour ; it is fometimes ufed in 
medicine. There has been one fpecies of Pfyllium or 
Fleawort found growing naturally in England, which 
is the fort ufed in medicine, which was in the earth 
thrown out of the bottom of the canals which were 
dug for the Chelfea water-works, where it grew in 
great plenty. The feeds of this muft have been bu- 
ried there feme ages, for no perfon remembers any of 
the plants growing in that neighbourhood before. 
The feeds of this are fometimes ufed, which are im- 
ported from the South of France. 
There are feverai varieties of all thefe three forts, 
which are fometimes preferved in botanic gardens, 
but having no beauty, they are not admitted into any 
other, fo I fhall pafs them over here, as being weeds 
wherever they are permitted to feed. 
PLANTAIN-TREE. See Musa. 
P LAN TING. Although the method of Planting 
the various forts of trees is fully fet down under their 
feverai articles, where each kind is mentioned, yet it 
may not be amifs to fay fomething in general upon 
that head in this place, which fliall be treated as briefly 
as poffible. And, 
Firft, the firft thing in Planting of trees is to prepare 
the ground (according to the different forts of trees in- 
tended to be planted) before the trees are taken out 
of the earth ; for you flionld fuffer them to remain as 
little time out of the ground as poffible. 
In taking up the trees you ftiould carefully dig away 
the eartfe round their roots, fo as to come at their fe- 
verai parts to cut them off ; for if they are torn out 
of the ground without care, the roots will be broken 
and bruifed very much to the great injury of the 
trees. When they are taken up, the next thing is to 
prepare them for Planting ; in doing of which there 
are two things to be principally regarded ; the one is 
to prepare the roots, and the other to prune their 
heads, in fuch a manner as may be moft ferviceable 
in promoting the future growth of the trees. 
And firft as to the roots ; all the fmall fibres are to 
be cut off as near to the place from whence they are 
produced as may be (excepting fuch trees as are to 
be replanted immediately after they are taken up;) 
other-wife the air will turn all the fmall roots and fibres 
black, which, if permitted to remain gn when the tree 
P L A 
is planted, will grow mouldy and decay, and thereby 
greatly injure the new fibres which are produced, fo 
that many times the trees mifearry for want of duly 
obferving this. After the fibres are cut off, all the 
bruifed or broken roots fhould be cut fmooth, other- 
wife they are apt to rot and diftemper the trees •, and 
all irregular roots which crofs each other, and the 
downright roots, (efpecially in fruit-trees) muft be 
cut off'; fo that when the roots are regularly 
pruned, they may in feme meafure refemble the 
fingers of a hand when fpread open ; then the 
larger roots fhould be fhortened in proportion to the 
age and ftrength of the tree, as alfo the particular forts 
of trees are to be confidered ; for the Walnut, Mul- 
berry, and feme other tender-rooted kinds fhould not 
be pruned fo clofe, as the more hardy forts of fruit or 
foreft-trees, which in young fruit-trees, fuch as Pears, 
Apples, Plums, Peaches, &c. that are one year old 
from budding or grafting, may be left about eight or 
nine inches long ; but in older trees they muft be left 
of a much greater length ; but this is to be under- 
flood of the larger roots only, for the fmall ones muft 
be quite cut out, or pruned very fhort. Their ex- 
treme parts, which are generally very weak, com- 
iponly decay after moving, fo that it is the better 
way entirely to difplace them. 
The next thing is the pruning of their heads, which 
muft be differently performed in different trees, for 
the defign of the trees muft alfo be confidered ; if they 
are fruit-trees, and intended for walls or efpaliers, it 
is the better way to plant them with the greateft part 
of their heads, which fhould remain on until the fpring, 
juft before the trees begin to fhoot, when they muft 
be cut down to five or fix eyes (as is fully inferred 
in the feverai articles of the various kinds of fruit) be- 
ing very careful, in doing of this, not to difturb the 
new roots. 
But if the trees are defigned for ftandards, you fhould 
prune oft' the fmall branches clofe to the places where 
they are produced ; as alfo irregular branches which 
crofs each other, and by their motion, whena gitated 
by the wind, rub and bruife their bark, fo as to occa- 
fion many times great wounds in thofe places ; befides, 
it makes a difagreeable appearance to the fight, and 
adds to the clofenefs of its head, which fhould al- 
ways be avoided in fruit-trees, whofe branches fhould 
be preferved as far diftant from each other, as they 
are ufually produced when in a regular way of growth, 
(which is in all forts of trees proportionable to the 
fize of their leaves, and magnitude of their fruit) for 
when their heads are very thick, which is often oc- 
cafioned by the unfkilful fhortening of their branches, 
the fun and air cannot freely pafs between the leaves, 
fo that the fruit muft be fmall and ill-tafted. But to 
return : after having difplaced . thefe branches, you 
fhould alfo cut off all fuch parts of branches, as have 
by accident been broken or wounded ; for thefe will 
remain a difagreeable fight, and often occafion a dif- 
eafe in the tree. But you fhould by no means cut off 
the main leading fhoots, as is by too many pradifed, 
for thofe are neceffary to attract the fap from the 
root, and thereby promote the growth of the tree ; 
for from feverai experiments which I made in the win- 
ter 1729, by cutting off the branches of feverai forts 
of trees, and putting them into phials filled with wa- 
ter, whofe tops were clofely covered to prevent the 
evaporating of the water, I found, that thofe fhoots, 
whofe leading buds w r ere preferved, did attract the 
moifture in much greater quantities than thofe fhoots 
whofe tops were cut off; and from feverai experi- 
ments made by the Rev. Dr. Hales, we find that 
great quantities of moifture are imbibed at wounds, 
where branches are cut oft' ; fo that by thus fhortening 
the branches, the wet, which generally falls in great plenty 
during the winter feafon,is plentifully imbibed, and for 
want of leaves to perfpire it off, mixes with the fap of 
trees, and thereby diftending the veffels, deftroys their 
contracting force, which many times kills the tree, or 
at leaft weakens it fo much as not to be recovered again 
for feme years, as I have feverai times obferved. 
