306 OX SEEDLINGS 



nerves uniting with the midrib at its apex. They are also con- 

 spicuously emarginate -with a tooth in the notch. The first 

 pair of leaves are suhorbicular and deeply incised with rounded 

 teeth. V. hederaefolia (fig. 566) has also exceptionally large 

 cotyledons, but they differ somewhat from any of the above in 

 being oblong-oval and only slightly, if at all, emarginata. The 

 large, concave seed and the mode of germination are shown in 

 fig. 565. Pentstemon Mackayanus has entire or slightly 

 emarginate cotyledons, and the first pair of leaves are broadly 

 ovate and entire. Another slight departure from the type is 

 met with in an unnamed species of Calceolaria, where the 

 cotyledons are somewhat broader than long, and the two first 

 leaves are broadly ovate and rather acutely serrate. 



The seedling of Scrophularia sambucifolia (fig. 557) closely 

 resembles that of some species of Salvia. The cotyledons are 

 roundly triangular and obtuse. The two first pairs of leaves 

 are cordate and crenate. The ultimate leaves are interruptedly 

 pinnatisect and lyrate ; the lower segments are small and 

 roundly cordate and crenate, while the terminal one is very 

 large and oblong-cordate; minute intermediate segments often 

 occur between the larger ones. The cotyledons of Torenia 

 Fournieri (fig. 561) are emarginate and slightly cordate at 

 the base, but otherwise shaped like those of the last species. 

 As they get very old they appear to lose the basal sinus and to 

 become more reniform. The leaves are all ovate and serrate. 



One of the most remarkable types is that in which the 

 cotyledons greatly enlarge by intercalary growth, and alter 

 their shape after germination, as happens in Streptocarpus, 

 and in several genera belonging to the Onagrarieae already 

 mentioned. I have noted it in Mimulus luteus (fig. 560) and in 

 Linaria. The cotyledons of the former are triangular and 

 incipiently trifid when full grown. The terminal tooth repre- 

 sents the original and true lamina of the cotyledons soon after 

 germination. The seedling itself is dimorphic according to 

 circumstances. If it has plenty of room to develop in the 

 seed-bed the primary leaves are triangular, while the inter- 

 nodes of the stem are hardly developed ; but if the seedlings 

 are crowded, the primary internodes elongate considerably and 

 the leaves become oval. 



