PAPAVERACE^E, OR POPPY TRIBE. 365 



are attached to a placenta, which springs from the wall, and not 

 from the centre of the seed-vessel, the placenta is said to be 

 parietal. In the true Poppies, the number of placentae, marking 

 the number of united carpels, is considerable ; but in a British 

 genus (Glaucium) commonly known as the Horned Poppy, the 

 ovary is formed of only two carpels grown together ; and these, 

 when ripe, look like long slender but stiff horns, whence the 

 common name is derived. The scientific name is founded on the 

 sea-green hue of the stems and leaves, which look as if the sur- 

 face had been encrusted with the salt spray. Allied to the 

 Horned Poppy (which grows chiefly on the sea- shore) is a plant 

 termed Celandine (Chelidonium)^ having pale green leaves and 

 rather small yellow flowers which grow in umbels (as in the tribe 

 of Umbelliferce, hereafter to be described), and frequenting waste 

 places, especially near towns and villages. This still more 

 departs from the ordinary type of the Poppy tribe, in the structure 

 of its seed-vessel ; which consists of a single pod separating when 

 ripe into two valves, as in the Pea tribe. 



525. A very curious anomaly is met with in a foreign genus 

 belonging to this order, the Eschscholtzia. The flower of this 

 plant, before it expands, is enclosed in a taper-pointed green 

 sheath, which is pushed off by degrees as the petals unfold, and 

 at last drops to the ground. This extinguisher- like organ would 

 seem to be something entirely new. If carefully examined, how- 

 ever, it is found to be nothing else than the calyx, of which the 

 two sepals have adhered so firmly, that they will not separate, 

 in the ordinary manner, to admit of the expansion of the flower; 

 and as it must be got rid of in some way, nature has provided 

 the means of throwing it off, by making its attachment weak at 

 the base, from which it is disengaged. This adhesion of two 

 parts growing in contact with each other, is a very common 

 occurrence in Plants ; and several instances of it will hereafter 

 occur. 



526. The plants of this order exhibit, in a greater or less 

 degree, the same tendency to variation, which has been noticed 

 in the Ranunculaceae. This is especially the case with the White 

 Poppy, which is cultivated in gardens on account of the showy 



