This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Of hardy Arums there are not many species. The spathe is always a conspicuous feature in the inflorescence of the genus, but not always an ornamental one. The spikes of fruit in some species, composed as they are of large red berries, are undoubtedly ornamental, however; and as they assume their greatest beauty in autumn and early winter, they are of some importance where colour is desirable out of doors at that season. These berries have a special value besides their ornamental quality. Those of A. maculatum are, according to Curtis, greedily eaten by pheasants, and it is also said that the roots are relished by them. A. italicum, which is nearly allied to, and closely resembles in berry and roots, maculatum, would probably be equally welcome to those birds. The whole order is remarkable for possessing acrid, burning, and poisonous properties; a few species, such as calamus, are exceptions, being aromatic and harmless. The species of Arum are all acrid and poisonous in the fresh state, but the poisonous qualities are dissipated by the process of drying, and the roots of several of the species form a wholesome farinaceous food when dried and cooked.
Those of Arum maculatum were in former days used to make starch, when not only ladies but gentlemen also thought it becoming to bedeck their necks and wrists with ruffs and frills. Gerard says it was "the most pure and white starch, but most hurtful for the hands of the laundresse that hath the handling of it, for it choppeth and blistereth and maketh the hands rough and rugged and withal smarting." The roots are also manufactured into "Portland sago" by the inhabitants of the island of that name, in which the plant is very plentiful. Arums are fit subjects for introducing into shrubbery borders in moist, partially-shaded places. They are easily cultivated, and where the conditions are favourable they are even apt to become troublesome as weeds, and should not therefore be placed in the neighbourhood of anything more choice than themselves. They are useful also for introducing into woods, if not too close and shady; for though shade-loving plants, they do not thrive long under dense shade. Increase by division of the roots.
A very singular subject, worthy on that score alone of a place among cultivated plants. It grows about 3 feet high. The leaves are dark green, deeply palmately divided, and the stalks are marked and spotted like the belly of a snake. The spathes are blackish brown, showing themselves clear above the foliage. The flowers have the unenviable distinction of being among the most offensively-odorous of flowers: they are equal to, if they do not actually surpass, carrion itself, in the effluvium they emit. Native of S. Europe.
This species grows from 1 foot to 18 inches high. The leaves are broadly arrow-shaped, veined, and often also spotted with white on a bright shining green ground. The berries are scarlet, in close spikes, supported on stout erect stalks, appearing at their best in late autumn and early winter. It is worthy of a place among choice and curious plants in shady borders. Native of Italy. It is a curious fact in connection with this plant, and perhaps with others of the family, if it is not general, that at the time of opening the spadix evolves a quantity of heat not only sufficient to affect the thermometer, if placed within the spathe, but to be distinctly appreciable to the hand also. What purpose this heat may serve in the economy of the plant, or whether it is a result rather than any agency, are points I believe not yet clearly settled. Lamarck was the first to point out the fact.
Besides the popular name just given, the following have been applied to this plant at different times and in different localities: Starch-wort, Wake Robin, Friar's Cowl, Lords and Ladies, and Priest's-pint. It grows about 9 inches high, with leaves of the same form as those of italicum, but smaller. The berries are similar to those of that species also, but both they and the spike are smaller: they appear about the same time. The usual colour of the spots, in the indigenous form, is black or blackish brown on a shining green ground; but there is a variety, peculiar to the Isle of Wight, in which the colour of the markings is the same as those of italicum. Some hold that it is that species naturalised, and somewhat altered by peculiar conditions. Mr Bentham, a most reliable authority, is of opinion that it is a peculiar local form of maculatum.