178 FLOWERS OF THE ROADSIDES AND HEDGES 
are small or ephemeral. The leaf-blade is lobed and toothed, the 
leaf glossy and glabrous. The bole has a smooth bark at first, which 
becomes divided into longitudinal furrows, often twisted and grey in 
colour. The trunk may divide. 
The flowers are white or pink, the inflorescence a corymbose cyme, 
being cylindrical with a flat top. Each flower has 5 united sepals, 5 
distinct white petals, 20 stamens, pink anthers becoming brown, and 
they are attached to the margin of a basin. The style (1 in this form) 
is central with a broad stigma. The scent is due to trimethylanin. 
The fruit is a haw or stone fruit, with 1 seed. The calyx is persistent 
at the top of the fruit. 
The tree is often 15 ft. high. The flowering period is May and 
June. A deciduous tree, it is perennial and increased by seeds. 
The honey is half-concealed, and is secreted by a ring at the base 
of the flower. The stigma ripens first. The flowers are strong- 
scented, and the smell is attractive to dung- and flesh-flies. The 
stamens are not ripe when the flower opens. ‘The outer are erect, the 
inner bent inwards, the anthers below the stigmas. The stigmas are, 
however, ripe and project in the centre, and the anthers ripen a few 
days after, opening inwards. The inner anthers when it is cold are 
bent down below the stigma after opening, the outer overtop the 
stigmas and are bent inward. But when it is fine the stamens bend 
outwards and then the honey disk is visible. If insects visit the flower 
they touch stamens and stigmas with opposite sides of the head and 
cross-pollination follows, but in their absence and in wet weather self- 
pollination is most probable. 
Sweet sap is exuded by the young shoots which insects seek. The 
visitors are numerous: Axthophora, Bombus, Andrena, Odynerus, 
Tachydromia, E-mpis, Microphorus, Pipiza, Rhingia, Evristalis, FLelo- 
philus, Xylota, Echinomyia, Sarcophaga, Onesia, Graphomyia, Mesent- 
brina, Cyrtoneura, Brbio, Dilophus, Attagenus, Anthrenus, Meligethes, 
Anthraxia, Malachius, Telephorus, Asclera, Anaspis, Mordella, Clytus, 
Grammoptera, Clythra, Halictus, Nomada, Eucera, and Apis. 
The fruit is edible, and dispersed by birds, &c. It is therefore 
spread largely by animal agency. 
Hawthorn is normally a sand plant living on a sand soil, but it 
is usually enriched by some humus which is accumulated under its 
own shade. 
The first stages of Gymnosporangium confusum and G. clavarie- 
forme grow on this plant. The second stage grows on Juniper in each 
case. The leaves are galled by E7zophyes crategz, EF. goniothorax, or 
