386 VARIOUS PLANT GROUPS 



ous bristles forming what is termed tlie pappus.^ Sometimes 

 through a prolongation of the torus above the fruit a sort of 

 parachute is formed as in lettuce (Lactuca, Fig. 76j. The 

 one-seeded fruit of Compositae is commonly called an achene, 

 although morphologically it is verj^ different from such a 

 simple achene as that of the crowfoots. 



In spite of wide diversities in structural detail the members 

 of this vast family may generally be recognized as herbs with 

 milky or watery juice; flowers in dense heads having a calyx-like 

 involucre, gamopetalous, regular or irregular; stamens five, 

 syngenesious, but loiih distinct filaments inserted on the corolla, 

 and the pollen-sacs straight; ovary inferior, with a single ovule; 

 fruit achenial, often with papptis. 



140. The bellflower order (Campanulales), includes several 

 families with flowers perfect, imperfect, or neutral, regular or 

 irregular, mostly gamopetalous; the stamens five, adherent to the 

 corolla, distinct or more or less coherent; anthers not poricidal; 

 ovary compound., inferior. 



The formula of Campanulales is given on pages 420, 421. 



141. The bellflower series (MetachlamydeEe) in contrast 

 with the crowfoot series or Archichlamydea;, includes several 

 orders which are characterized by the prevalence of a gamo- 

 petalous corolla. This, as showing a more advanced develop- 

 ment of the perianth than we find in archichlamydeous flowers 

 (see section 129), entitles the flower possessing it to be dis- 

 tinguished as inctachlamydeous.- 



142. The dicotyl sub-class (Dicotyledones) comprises the 

 crowfoot series (Archiclilam3'dese) and the bellflower scries 

 (Metachlamj^dea^). These agree in being made up of seed 

 plants with the embryo having two cot.yledons or dicotyled- 

 onous.^ The parts of the flower are very generally in fours 

 or fives, seldom in threes; the leaves are mostly netted- 

 veined; and in the stem there may be distinguished a central 

 core of pith surrounded by a ring or rings of wood and bark. 

 See especially Figs. 232 and 233. Stems thus constructed 



' Pap'-pus > Gr. pappos, grandfather, applied to the thistledown in 

 allusion to white hair. STCj. 



^ Mct'-a-chla-myd"-e-ous < Gr. mela, beyond. 



' Di"(!ot-y-led'on-ou8 < Gr. dts, two; /co(j/Wo?!, seed-leaf. 



