SHOOTS 



79 



nation and seed-di»trihufion. 

 It is necessary to call attention 

 to certain pecnliar features of 

 this type of stem. 



50. Structures. — The joints 

 of the stem do not spread 

 apart, so that the peculiar 

 leaves are kept close together, 

 usually forming a rosette-like 

 cluster (see Fig. 71). These 

 leaves are of four kinds : the 

 lowest (outermost) ones (indi- 

 vidually sejiah. collectively 

 calijx) mostly resemble snudl 

 foliage leaves ; the next higher 

 (inner) set (individual]yji9f/ft/,s, 

 collectively corolla) are usually 

 the most ('onspicuous, delicate 

 in textui'c and brightly col- 

 ored ; the third set {stamens) 

 produces the pollen ; the 

 highest (innermost) set {car- 

 pels) form the pistil and pro- 

 duce the ovules, •which are to 

 become seeds. These four sets 

 may not all lie present in the 

 same flower ; the members of 

 the same set may be more or 

 less blended with one another, 

 fornung tubes, urns, etc. (see 



Fitrs. 



::), 74) : or the dif- 



ferent memljers may be modi- 

 fied in the greatest variety of 

 ways. 



Another peculiarity of this 

 typo of stem is that when the 



Fig. 7:3. A trroii]) of rlowerp of tlu- rose 

 family. Tlie one at Hit lojj i I'ulin- 

 t'iUa} show.s three liroael sepals, 

 n:iuch smaller petals alternating 

 ^\■ith them, a group of stamens, and 

 a large receptacle bearing luimer- 

 ous small carpels. The central one 

 {Ak'htmilla) shows the tips of two 

 small sepals, three larger petals 

 united below, stamens arising from 

 the rim of tlieurn, and a single pe- 

 culiar pistil. The lowest flower (the 

 common apple) shows the sepals, 

 petals, stamens, and three styles, 

 all arising from the ON'ary part of 

 the pistil.— After Focke, 



