The Opium Poppy (Papaver somniferum) differs from the Corn Poppy in several respects. First, the whole plant is glabrous, that is, devoid of either hairs or bristles; the capsule also is much larger and more fleshy in an unripe state, and the crown-like lid is smoother, and curved over like a plume of feathers, (see a in fig. 112.)
Fig. 112.—The flower, bud, leaves, and capsule of the Opium Poppy, much smaller than the natural size.
The fleshiness of the unripe seed-vessel of the Poppy puzzled me extremely at first, as I knew that the ripe capsule of this Poppy is always dry and leathery; but it was soon explained to me, that this fleshy substance is, in fact, an elongation of the receptacle or disk, which rises up round the carpels, and envelops them, in the same way as the disk of the Water-lily grows round the pistil and carpels of that plant, but which dries up as the fruit ripens. The leaves of the Opium Poppy (b) differ from those of the Corn Poppy, in being much broader, and only slightly cut or notched; they are also glaucous, that is, of a bluish or sea-green, and they are clasped round the stem at their base (as shown at c). All the Papaveraceæ abound in a thick glutinous juice, which in the Poppies has the colour and appearance of milk, and which possesses stupifying properties; but in the Opium Poppy this juice is particularly abundant. Opium is, in fact, procured by wounding the fleshy capsule with a sharp knife, and suffering the milky juice which exudes to dry in the sun; after which it is scraped off with a blunt instrument, and pressed into cakes for sale. The opium of commerce is produced in hot countries; but even in England, any one who chooses may procure a small quantity of opium, by wounding the fleshy capsule of the common White Poppy when it is about half ripe. A milky juice will issue from the wound, which when dry becomes opium, and would be poisonous if taken in excess. The capsule of the White or Opium Poppy has, when ripe, a little window-like opening under each stigma for the discharge of the seeds, which contain abundance of oil, and may be safely eaten, though the rest of the plant is poisonous.
There are many different kinds of Poppy; but they all agree in the corolla of their flowers being in four petals, or in some number divisible by four; and in the calyx, which is generally in two sepals, dropping off as soon as the flowers expand. All the species abound in a milky juice, which poisons by stupifying; and they all agree in the general construction of the capsule, with its fleshy envelop and its stigma-formed lid. The petals are always crumpled in the bud, and they fall very soon, so that the beauty of the flowers is very short-lived. The flower-buds droop; but when the flowers expand, the stalk becomes erect, and remains so while the capsule containing the seeds is ripening; a wise provision, common to many plants, to prevent the seeds from falling too soon. The calyx of most of the Poppies is in only two sepals; but in the two showy perennial species, called P. orientale and P. bracteatum, the calyx is in three sepals.
Among the other plants belonging to the order Papaveraceæ, may be mentioned the Horned Poppy (Glaucium luteum), which, instead of an obovate capsule, has a long horn-like pod, divided into two cells, the valves opening from the top to the bottom. The whole plant is glaucous; and the leaves, which are broad and notched, clasp the stem at their base, like those of the Opium Poppy. The Prickly Poppy (Argemone mexicana) has the whole plant covered with strong prickles; the leaves are wrinkled and curved up at the margin; the calyx has three sepals; and the capsules are in four or five valves, the stigmas forming a kind of cross at the top. The stem and leaves when bruised give out a thick glutinous juice, which, instead of being white like that of the Poppy, is yellow.
The Eschscholtzia is the last genus of the order Papaveraceæ that I shall mention here, and it deserves a particular description, both from its popularity and the beauty of its flowers, and from the singularity of its botanical construction. The bud when it first appears is enfolded in a calyx, which is pointed at its upper extremity, and appears to have a kind of rim near its base. When the flower is ready to expand, the calyx detaches itself all round from the projecting rim, and rises gradually without opening, till the flower actually pushes it off. The detached calyx resembles an extinguisher, and hence it is called calyptrate, which has that signification. The flower is cup-shaped; there are four petals and four stigmas, two of which are much longer than the others. The capsules are elongated like those of the Horned Poppy, but they are distinguished by the projection of the flat fleshy disk at their base; they are two-valved and two-celled. The leaves are glaucous, and finely cut. There are three species, or perhaps varieties, which differ principally in the degree of enlargement of the receptacle or disk. They have all large fleshy roots, which bleed copiously if wounded, and for this reason the plants are difficult to remove unless when quite young.