286 



MALEORMATIDNS A'K^D DISEASES 



tinctly seen in Asparagus. The union of the flowers on the 

 summit of such fascicular stems favours this explanation ; 

 since the Hieracium already mentioned, as well as the Ranun- 

 culus hulbosus, shew distinctly this union of the flowers; 

 (Gilibert Demonstr. elem. de Bot.) 



412. 



Among malformations, we place also the discoloration of 

 the leaves, particularly the fascicular streaks, the silvery or 

 golden margins, and many other varieties of spots which are 

 common among garden plants,— as in Myrtle, Sage, Ivy, 

 Holly, the Agave Americana, Sempervivum arboreum, and 

 many of the Pelargoniae. These spots are not diseases, be- 

 cause the whole plant has all the signs of being in a perfect- 

 ly healthy state. But neither are they effects of a law of na- 

 ture, like the spots of Orchis maculata, and the red coloured 

 leaves of Caladium hicolor and Amaranthus tricolor, be- 

 cause they are not continued by propagation. But it is like- 

 ly that such discoloured spots are incapable of performing 

 their function, namely, the exhalation of oxygen gas, as in- 

 deed experiments shew ; (Sennebier, Physiologie Vegetale, 

 iv. p. 273. 



413. 



Luxuriancy of growth produces a manifold subdivision of 

 the leaves and a curling of their margin, as we find strikingly 

 exemplified in Polypodium cambricum, Scolopendrium offici- 

 oialey Acer platanoides, and Fraxinus excelsior. We can- 

 not consider these forms as permanent, or form peculiar 

 species from them, because they are by no means propagated 

 by seed, but only by buds and layers. The manifold inden- 

 tations of the leaves of the common Alder, and of the Pim- 

 pinella saxifraga, are of the same nature, and, on account of 

 their little durability, deserve to be considered rather as va- 

 rieties. 



414. 



Retrogradations sometimes occur in vegetation (Goethens 

 unregelmassige Metamorphose), when the more perfect organs 



