==Disease of Hollyhocks and Malvaceous Plants.==—­In some parts of England the cultivation of the Hollyhock had at one time quite ceased owing to the attacks of a microscopic fungus named =Puccinia malvacearum=.  In gardens and nurseries, where years ago Hollyhocks were one of the chief ornaments of the place, it became impossible to grow a single plant.  The disease is not confined to the Hollyhock, for it attacks many malvaceous plants, notably the Mallows of our hedgesides.  We have seen plants of the white variety of the Musk Mallow (=Malva moschata=) totally destroyed by this parasite.  The home of the Hollyhock fungus is Chili, whence the Potato fungus reached us.  The Hollyhock fungus first attacked the malvaceous plants of Australia, and then reached England in 1873 by the continent of Europe.  The best and cleanest seeds of the Hollyhock should be purchased.

[Illustration:  Fungus of hollyhock disease =Puccinia malvacearum=]

A fragment of a Hollyhock leaf is illustrated at A, dotted with the characteristic brown pustules; these pustules cover the stems as well as the leaves.  At B is shown the edge of a pustule enlarged one hundred diameters and seen in section; to show the whole of a pustule in section from six inches to a foot of space would be required.  Bursting through the skin of the plant may be seen a dense forest of threads, each thread bearing a spore with a joint across the middle.  One pustule alone will produce thousands of these double spores.  At C some of the threads and spores are still further enlarged to two hundred diameters, and at D one ripe spore is shown falling from the thread and breaking asunder—­each piece is a reproductive body or spore.  When mature, these minute spores or ‘seeds’ are carried in the air by millions.  At E one of the compound spores is enlarged to four hundred diameters.  As this disease is seated within the tissues of the plant, remedies are difficult of application, and in many cases attempts at cure have failed.  No doubt the fungus is nursed by malvaceous weeds.  Infected Hollyhock plants and allied weeds should be destroyed by fire or by deep burying.

==Poppy Disease.==—­Garden Poppies are often attacked by a fungus pest closely allied to the fungus of the Potato disease, and named =Peronospora arborescens=.  It grows sometimes in abundance on the common Red Poppy of cornfields (=Papaver Rhoeas=), and it badly attacks =P. somniferum= and all its garden varieties.  The fungus grows within the leaves, and emerges with a tree-like growth through the organs of transpiration (the stomates) on the under side of the leaves.  Like the fungus of the Potato disease, it speedily sets up decomposition, and destroys the host-plant.

[Illustration:  Fungus of poppy disease

=Peronospora arborescens=]