THE WOOD SORREL — continued. 
very vivid green, are markedly obcordate or heart-shaped, are scattered over 
with soft hairs, and are often reddened or purpled on their under surfaces with 
anthocyan, which serves probably to convert light rays into heat, and thus enables 
the plant to manufacture its food in the cooler months of the year. These leaves 
are not sensitive to mere touch as are those of some species, such as the allied 
Indian Biophylum sensitivum De Candolle ; but, if the sky is overcast, or at night, 
they fold each leaflet down its midrib and droop them into three vertical planes, 
thus exposing the minimum of surface to radiation. 
Whilst in other species the flowers are often in umbellate clusters, in the Wood 
Sorrel they rise solitarily from the rhizome, on reddish peduncles, rather longer than 
the leaf-stalks, with two bracts about the middle of their length. In dull or cold 
weather the flowers close ; and, in addition to the beautiful delicate blossoms of 
May, cleistogene flowers are produced later on. The obovate petals cohere at their 
bases and are veined, or sometimes deeply tinged, with pink or pale violet, and they 
secrete nectar from a gland projecting at the base of each. The flowers are said 
only to remain open, under ordinary circumstances, from nine in the morning to six 
in the evening, but they are not much visited by insects ; and, as in this species, 
anthers and stigmas mature simultaneously, or nearly so, self-pollination is probably 
frequent. After fertilisation, the peduncle bends downwards ; but, when the capsule 
is ripe, it once more bends upwards. The capsules of the short-stalked cleistogene 
flowers, however, bury themselves in the ground. 
The five-sided, five-chambered capsule contains two or three seeds in each 
chamber. Each seed develops a fleshy aril from its base ; and when the polished 
black seeds are ripe, and the capsule splits down the five midribs of its carpels, the 
inner tissue of this aril becomes tense and splits, turning inside out but remaining 
attached to the placenta, while the seed is thrown to a considerable distance. 
The shape of the leaflets obviously gives rise to the Border name of Hearts; 
while the uncommon Sleeping Beauty takes account of their movements. Flourishing 
as the plant often does in the humus derived from the decaying wood, bark, and 
leaves of an old stump, the old name of Stubwort seems appropriate. Most of the 
numerous popular names for the species refer, however, to the acidity of the three 
leaflets or their development about the time when the cuckoo arrives. Such are the 
German Sauerklee, the Portuguese Trevo azedo, and the Dutch Zuurklaver ; our English 
Cuckoo’ s-meat or Gowk’ s-meat, the French Pain de coucou, the Swedish Giokmat, and the 
Dutch Koeks-koeks-brood. The pretty name Alleluia is explained by Gerard as 
“ By reason when it springeth forth and flowreth . . . Alleluja was woont to be sung in churches ” ; 
though it has been suggested that this is merely a corruption of the Calabrian name 
luliola and the apothecaries’ form Lujula or Luzula. 
