Chemistry of Essential Oils

488 THE CHEMISTRY OF ESSENTIAL OILS

Pelargonium graveolens, is grown. Pelargonium capitatum is usually
named in literature as the parent plant of " geranium rosat," but accord-
ing to R. Knuth this is an error, Pelargonium capitatum being a hybrid
of Pelargonium graveolens.
The geranium is propagated in Algeria by cuttings, but it is not neces-
sary to renew the plantations every year, as is done in the South of
France, for the climate of Algeria is rather warmer, and the plants are
therefore not killed by frost in the winter. It is said that in Mitidja the
plant sometimes attains an age of twelve years. It often happens, as for
instance in 1911-12, that the plant is in leaf throughout the year, but
there are occasions in Algeria when the geranium plantations suffer
severely from frost. In the South of France the geranium is treated as
an annual; that is to say, every spring the fields are planted with fresh
cuttings, which have been taken during the autumn and left to winter
in protected spots. In the South of France there is only one crop yearly
(in the autumn), but in Algeria three crops are gathered every year.
In the South of France it is necessary to have recourse to intensive cul-
ture by irrigation and rich manuring, in order to make the single crop
pay. In Algeria the flowers are cut for the first time in early spring;
the second cut is in June, and the third, if any, in October and November.

In addition to suffering from the ravages of insects, the pelargonium
plants are frequently attacked by Cuscuta, a parasitic plant belonging to
the family of the Convolvulacece. It is also said that species of Orobanche
(N.O. Scrophulariacece) thrive upon the geranium plants. On the other
hand, according to Ducellier, the O^mm-species, which afflicts garden
geraniums, has neither been observed in Algeria nor in other districts
where the geranium is grown for distilling.
The oil yield varies according to the conditions of the soil. The
average estimate in Algeria is from 20 to 30 kilos per hectare, of which
the first cut yields 20 kilos and the second (and eventually also the third)
from 10 to 12 kilos. Yields of 40, and even of 50 kilos oil per hectare,
have been recorded.
Holmes has examined the following well-marked species. The
odours have been classified by Umney and Holmes as under :—

Species Examined.

Pelar gonium capitatum.

Abbotsbury Seedling

Rose Unique

Rollison Unique

Attar of Rose

Shrubland Pet.

Radula " Syon "

„ var. roseum

,, var. majus

Blandfordianum

odoratissimnm

fulgidum

graveolens.

Little Gem.

Lady Plymouth

denticulatum

,, var. Sandbach

quercifolium

„ Clorinde

,, (unnamed

Description of Odour.

Rose and diphenyl ether

Similar odour

Fine rose odour

Rose

Strong rose

Rose and faint strawberry

Strong diphenyl ether and rose

,, rose and faint ladanum

,, geranium and faint pepper-

mint

Paint rose

Tansy and faint rose

Butyric

Rose and rue, slight peppermint

Peppermint, no rose

»» )»

Rose and ladanum, slight butyric

Gitronellal, „ „ „

Ladanum

Pepper and southernwood

var.). Parsley