TREVERINA. 
all land whose subsoil is compact, stiff, and 
almost wholly destitute of humus—requires to 
be done with judgment and caution; and yet, 
when thus done, is proportionally more benefi- 
cial than even the complete, mechanical turn- 
ing upside down of very deep loamy mould. 
“Tet us take the worst possible state of ground 
| for the trenching operation,—bad, poor, sour 
land which, in its present state, will grow no- 
thing well. A little of it might be brought to 
the top every time the earth is dug, because 
exposing even bad soil to the atmosphere will im- 
prove it; and if good ground reached only ten or 
a dozen inches down, this, when we begin to dig, 
must be removed one trench wide for the first 
operation, for the purpose of filling in the last 
left trench. This being removed for a start, in 
ordinary digging, the next spit dug all along 
would fill it up, and the ground would be merely 
turned over; but before we go at the second 
spit, it would be wise to dig up the bottom and 
leave it there; for next to bringing it to the 
top, loosening it at the bottom is best; but tak- 
ing out about two inches, to put on the top of 
the good soil, will be found an excellent mode of 
improving the ground permanently. Then dig 
the second spit along the space to be trenched, 
and throw it into the trench ; loosen the bottom 
again, and throw two inches of the stuff on the 
top of the good soil; continue this aJl through, 
one trench after another, until it is all finished, 
and the result will be, that this small quantity 
of worthless stuff will become, by the dressing 
and the exposure, workable and useful. In time 
-| two more inches might be brought up, and when 
it has become well mixed and amalgamated with 
the better soil, and the dung which is from time 
to time put on it, the soil which has been for 
years called shallow and unprofitable, will be far 
better than the owner could anticipate. In gra- 
velly soil, the ground would soon become stony, 
but excellent produce will come off stony ground ; 
and by picking the largest off from time to time, 
even the gravel brought up will be anything 
but unprofitable in the culture. The worse the 
ground is in its subsoil, the less must be brought 
up from time to time ; but whether clay, gravel, 
or chalk, attention to these matters will be 
repaid by a deeper cultivable soil; and by pro- 
per dressings according to its nature, additional 
produce will be obtained.” See the article SpapE- 
HuvsBANDRY. 
TRENCH-PLOUGHING. See Sussoir-Proven- 
ING. 
TREPANNING. See Hyparip. 
TREVERINA. A splendid, tropical, scarlet- 
flowered, evergreen, herbaceous plant, of the fig- 
wort family. It constitutes a genus of itself, 
and bears the specific name of coccinea, or ‘the 
scarlet ;’ but it is called by some botanists Cyrilla 
pulchella. It was introduced to Britain from 
Jamaica in 1778; and has long been a favourite 
TRICHOCENTRUM. 
487 
20 inches, and blooms in September; and it 
loves a soil of loamy peat, and is propagated by 
division of the roots. 
TRIANDRIA. See Borany. 
TRIANTHEMA. A genus of curious, exotic, 
green-flowered plants, of the purslane tribe. 
The monogynous species, 7. monogyna, is a na- 
tive of both Indies, and was introduced to Bri- 
tain from Jamaica in 1820. It is an annual, 
of about a foot in height, and blooms in May 
and June. Its root is bitter and slightly nause- 
ous, and is used in India in combination with 
ginger as a cathartic; its branches lie flat on 
the ground ; and its general appearance is simi- 
lar to that of common purslane. Some other 
specimens have been introduced to British col- 
lections. 
TRIAS. A genus of ornamental, tropical, epi- 
phytous plants, of the malaxis division of the 
orchis family. The name alludes to the trian- 
gular form of the open flower. The oblong spe- 
cies, 7’. oblonga, is a very handsome plant, with 
dingy green and purple flowers, blooming in No- 
vember; and was introduced to the orchideous 
collections of Britain a number of years ago from 
India. 
TRIBES. See Crasstrrcatron. 
TRIBRACHYA. A curious, tropical, green- 
flowered epiphyte, of the orchis family. It was 
introduced to British gardens from Sierra Leone 
in 1823; it has a height of only three or four 
inches, and blooms from midsummer till Novem- 
ber; and it constitutes a genus of itself, and is 
specifically called the pendulous. Its generic 
name signifies ‘ three-armed,’ and alludes to its 
spikes. 
TRIBULUS.. See Canrrops. 
TRICHATA. A hardy perennial grass, of the 
oat tribe. It constitutes a genus of itself, and 
is specifically called the ovate; it was introduced 
to Britain from the South of Kurope about 25 
years ago; and it blooms from midsummer till 
August; but it possesses little or no economical 
interest. 
TRICHILIA. A genus of ornamental, exotic, 
white-flowered, evergreen tall shrubs and small 
trees, of the bead-tree tribe. Five or six spe- 
cles, varying in height from 15 to 25 feet, and 
all blooming in June and July, and propagable 
from cuttings, have been introduced to British 
collections from the West Indies and Australia; 
and upwards of a dozen other species are known. 
The name trichilia is formed from a word signi- 
fying ‘ternary, and alludes to the triple cell 
and triple valve of the capsule. A warm oil, 
prepared from the fruit of the thorny species, 7’. 
spinosa, is regarded in India as a valuable appli- 
cation in cases of paralysis and of chronic rheu- 
matism. 
TRICHOCENTRUM. A genus of curious, 
exotic, epiphytous plants of the orchis family. 
Several species have been introduced to British 
gardens since 1834; and one of the first-flower- 
with amateur florists, It has a height of about 
cs 
