A HISTORY OF ESSEX appear the marine species occurs also high up on mountains. Common thrift (Armeria marifima), which grows abundantly on our saltings, covered at every tide by salt water, also flourishes high up on mountains, where the conditions of soil and climate must be very different ; in fact it is difficult to imagine localities affording wider differences. In the sea plantain (Plantago maritima) and scurvy grass (Cochlearia officinalis] we have also two plants which flourish on our saltings and high up on mountains. The species of Atriplex on our coast should also provide material for investigation. On our sandy shores there is a wide range of variations, and inland another series of variations. The sandworts (Spergularia) give four forms : S. rubra^ growing in hot, sandy, inland situations ; S. sa/igna, found in muddy or rocky situations by the sea ; S. media, occurring on muddy sea marshes; and lastly a species found only in rocky places by the sea, S. rupestris. It is scarcely necessary to say that this latter does not occur in Essex. These plants are so closely related that botanists do not agree in dividing them into species and varieties, but the inland forms are quite distinct from the marine forms. It will thus be seen that the coast flora of Essex offers problems of great scientific interest. Insectivorous plants mostly occurring in bogs are represented in the county, though rare. We have the sundew (Drosera rotundifolia), the great bladderwort (Utricularia vulgaris), rue-leaved saxifrage (Saxi- fraga tridactylites), and that remarkable plant the tooth wort (Lathraa squamaria), which obtains its vegetable diet from the roots of plants to which it attaches itself, and its animal nourishment by catching small insects in its scale-like leaves, folded back at the edges to form traps for unwary insects. The plant only needs to come above the ground in the spring to form flowers and seeds, not requiring green leaves like other plants. Orchids remarkable for the mechanism of their flowers by which their fertilization is accomplished are well represented in the county, though not so abundant as in some of the southern counties of England. The poisonous plants growing in the county are both of scientific and also of practical interest to the farmer and country resident. They may be summarized as follows : The poppy, which is unwholesome, though not so deadly as those species favouring hot climates ; the com- mon celandine, which is an acrid and violent irritant ; the soapwort ; the Deptford pink ; the white campion, the red campion, and most plants of the natural order Caryophylleas, which contain the active principle saponine and are therefore either poisonous or unwholesome. Fortunately saponine is destroyed by heating, hence flour made from corn containing seeds of these plants is rendered harmless by cooking. Holly berries cause violent irritation of the bowels. The leafless vetchling (Latbyrus ap/jaca), the rough-podded vetchling (L. birsutus], and the broom (Cytisus Scoparius) are the only British plants of the pea-flower tribe which have been known to possess deleterious qualities, causing violent headache 40
