254 
On Dodder. 
shaped embryo. Gaertner first stowed ttat, while these plants 
agreed in every way with other dicotyledons, they differed in 
the fundamental character expressed in the name, in having, 
as he supposed, only a single cotyledon in the embryo plant, but 
in reality this supposed cotyledon is only the axis or stem of the 
plant, without any leaf appendage whatever. 
As all the dodders are annual, and they have no roots pro- 
tected in the ground, the winter completely kills all the plants 
of each season's growth. The ripe seeds, however, supply the 
means in them, as in other annuals, of reproducing with the new 
season the destroyed plants of the last — for each perfect seed 
contains a minute bud capable, though separated from the parent 
plant, of maintaining a dormant existence, and, under suitable 
conditions, of starting into independent active life. Each seed 
encloses, either in the tissues of the embryo plant or surrounding 
,it, a quantity of food sufficient to support the young plant until 
its organs are developed so far as to obtain its own food. 
In Cuscuta, the albumen in which the embryo is enclosed 
supplies it with food enough to enable it to lay hold of the 
stem or branch from which it will draw its nourishment, if that 
is within reach. It is unable to maintain its life after this stock 
of food laid up by the parent is exhausted, so that it dies if it 
does not succeed in attaching itself to a living plant. Mr. 
Buckman has shown that, when sown with seeds of suitable plants, 
the ordinary internodal lengthening of the supporting stem lifts 
with it the young parasite from the earth. When, on the other 
hand, it attaches itself to grown plants, all connection with the 
earth is speedily cut off, and the lower extremity of the 'fili- 
form stem is left suspended from the nourishing plant. 
When the dodder touches the supporting plant it twines 
round the stem, and from the inner surface of the coil throws 
out a series of suckers, by which it secures a living connection 
with the stem. Through these suckers it withdraws the ela- 
borated juices from the plant for its own use, and, from its rapid 
growth, it soon impoverishes, and ultimately kills, the supporting 
plant. It has already, however, thrown out branches by which 
it has seized hold of new plants, and it continues to extend its 
relations as long as the season permits the parasite itself to live. 
In this way a single plant, by its rapid growth, will cover in 
time several square feet of ground, and impoverish, or com- 
pletely destroy, a great number of plants belonging to different 
natural orders. The most common British species, Cuscuta 
epifhi/mum, Murray (of which the trefoil dodder, C, trifolii, 
Bab., is only a variety), was first noticed, as its name almost 
implies, growing on thyme, but it is found on other and very 
different plants, as on furze, broom, trefoil, lucerne, rock-rose 
