This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Intimately connected as the flowering periods and duration of all plants are, as has been seen in the case of the groups of plants chosen to illustrate each habitat, no section reveals this more forcibly than the present one.
The plants that make it up are of four types: annuals, biennials, triennials, and perennials, and the three former greatly exceed the last. It is to be emphasized here that the annuals do not bloom till June. They have to produce from seed all the organs necessary for plant-life with growth and power of reproduction; whereas perennials have a root and rootstock and stem base already made, and in some cases the leaves persist, or at least the branches, whilst a fresh stock of radical leaves often arises in autumn to protect the new aerial stem or shoot of next year, e.g. Sisymbrium, Barbarea, Bal-lota, Rumex, etc, and in a mild winter these survive, and serve as an asset in spring.
The annual plants described are Shepherd's Purse, Mouse-ear Chickweed, Melilot, Stinking Mayweed, Groundsel, Musk Thistle, Hawksbeard, Purple Dead Nettle, Fat Hen, Wall Barley. The biennial plants are Burdock, Spear Thistle, Hound's Tongue, Viper's Bugloss, Mullein, all plants that are clothed with down or hairs. Milk Thistle and Henbane are triennial. Belladonna is also apparently biennial in some cases.
The perennials include Greater Celandine, Mallow, Stork's Bill, Goutweed, Tansy, Chicory, Bittersweet, Belladonna (usually), Creeping Toadflax, Toadflax, White Dead Nettle, Good King Henry, Dairy Maid's Dock. It is curious that in some genera only one species, e.g. Good King Henry, should be perennial, the rest annual. It is highly probable that all were perennial at first.
The mixture of waste-ground plants, which in many cases consists of plants distributed owing to certain properties they possess, causes a considerable diversity in their degree of attractiveness to insects, apart from the possession of honey, pollen, or sweet juices.
As a whole the flowers may be said to be conspicuous and brilliantly coloured, and some, as the Mallow, are wide open and large. Rather large flowers or flowerheads are also not uncommon, as in Greater Celandine, Melilot, Tansy, all yellow, Musk Thistle, Spear Thistle, Milk Thistle, Chicory, Viper's Bugloss. Three poisonous plants, Bittersweet, Belladonna, Henbane, have noxious aromas, and so has Hound's Tongue, and abnormal colours. The closed flowers of the Toadflaxes, and hooded flowers of the Dead Nettles, are all adapted to insect visits.
Shepherd's Purse and Mouse-ear Chickweed, with inconspicuous small flowers, are adapted equally to self- or cross-pollination, and Stork's Bill also, as well as Groundsel. Goutweed, Stinking Mayweed, Burdock, Hawksbeard, all have more or less conspicuous, though not such brilliant or large flowers. In Mouse-ear Chickweed and Mallow and Stork's Bill the anthers are ripe first. The Musk Thistle is a dioecious plant. In the Purple Dead Nettle the anthers and stigma mature simultaneously, and the same applies to Knotgrass, which has also cleistogamic flowers. The Goosefoots, Fat Hen, and Good King Henry, the Dairy Maid's Dock, and Wall Barley are pollinated by the agency of the wind. The rest are adapted to insect visits, or failing such they are in some cases self-fertile.