274 



HUTCHINSON'S POPULAR BOTANY 



FIG. 333. DWARF MALLOW. 

 Orbicular or sub-rotund leaf. 



are called auriculate. This plant is not the 

 Deadly Nightshade, but persons are said to 

 have been poisoned by eating its roots. 



There, within a finger's length of the 

 nearer of the Tropaeolums, is a Saxifrage ; 

 but not the one which we were wanting just 

 now. It is the kidney-shaped species tSaxi- 

 fraga geum), and the sharply toothed or dentate 

 margins of its leaves should receive attention, 

 as they are the first instances of such a 

 margin that have come before us. You will 



perceive that the teeth point outwards, and not, like the teeth in a serrated 

 margin, towards the apex of the leaf. 



It is fortunate that the garden contains a specimen of the Tulip-tree 

 (Liriodendron tuHpifera). Notice the curiously abrupt or truncated ter- 

 mination of the leaves, which gives them the appearance of having their 

 upper extremities cut off. No plant furnishes better examples of a trun- 

 cfite leaf than this. We would press the importance of always noting 

 the forms of leaf apices when preparing schedules of plants. Trivial 

 points of this kind are often of assistance in determining species and 



varieties. In addition to the forms already 

 described namely, the mucronate, emarginate, 

 and truncate four others may be briefly al- 

 luded to. Two of these the acute and obtuse 

 (i.e. blunted) are extremely common, and 

 hardly need to be described : the third is the 

 return, which differs from the obtuse in having 

 a broad, shallow notch in the middle, as may 

 be seen in the leaves of the Red Whortleberry 

 1 Vaccinium vitis-idcea) : and lastly the acumin- 

 ate, in which the apex narrows suddenly and 

 lengthens into a point or acumen. A some- 

 what extreme example of the latter form is 

 furnished by the Mexican shrub Phyllonoma 

 ruscifolium, which, however (as we saw earlier), 

 is chiefly interesting because of the peculiar 

 growth of its flowers, which are produced in 

 little bunches on the upper surface of the 

 midrib, just below the base of the acumen. 

 If, as some have suggested, the lower part of 

 the leaf is really a cladode, then the acumen 

 alone is the true leaf, and should be described 

 as lance-shaped rather than acuminate. How- 

 ever, it is quite unnecessary to go so far afield 



FlG. 334. PlMPERXEL. 



With opposite and decussate leaves, each 

 pair crossing those above and_below it. 



