Botany, or, The modern study of plants / by Marie Stopes.

  • Stopes, Marie Carmichael, 1880-1958.
Date:
1912
Catalogue details

Licence: In copyright

Credit: Botany, or, The modern study of plants / by Marie Stopes. Source: Wellcome Collection.

    79/104 (page 75)
    Also of the nature of an accident are the various forms of poisoning that may happen to healthy plants. They may be poisoned by gases in the atmosphere, or they may be poisoned by minerals in the sod. In the cases of slow poisoning the growth of the tissues may be arrested or altered and truly pathological conditions set in, in which abnormal cell grovd)hs take place. On the other hand, where the poison is stronger, the plants simply die, as, for instance, when the paths are sprinkled with weed-destroying compounds. These enter the roots in the osmotic process of root absorption, and travel tlirough the cells of the tissues. Accidents may happen to the healthiest individuals ; the pathologist is more concerned with the diseased ones and with those where the tissues are abnormal. One of the most fatal diseases that can overtake a plant is Chlorosis^ or the lack of colouring matter. This disease, in its essentials, is very similar to anaemia in human beings, and as the plants depend on their colour- ing matter for the manufacture of their own food, an extreme case cannot survive at all. Chlorosis is an obscure disease, but in some cases it certainly appears to be caused by a lack of iron, and without iron the human blood is not red nor plant granules green. Generally the seedlings attacked by the disease die out very early, but sometimes sickly whitish-leaved specimens struggle along for a little while. The disease is often local, and in compound leaves one leaflet here and there may be entirely colourless. This character is best seen in the gardeners’ “ variegated ” varieties, where the leaves are mottled or striped with cream-coloured patches and bands. The green parts there do enough work to carry on the life of the individual, while the colourless parts are non-producers. If this is not carried too far