Okder 101.— marvelworts. 276 



COHORT III. 



THE APETALOTJS EXOGENS. 



Essential Cha/raGter. — Flowering plants (Ph^nogamia), 

 with their stems growing by additions to the outside and the 

 wood in circular layers (Exogens), with the seeds inclosed in 

 seed-vessels (Angiospbems), and the flowers destitute of petals 

 (Apetai^). 



Oedeh' C— ARISTOLOCHIACE^. Birthworts. 



Low Tierbs or climbing shrubs with, alternate leaves, large flowers ,\ 

 calyx adhering to the ovary, valvate ia bud, brown or dull colored ; 

 stamens 6-12, at top. of the 6-ceIled, many-seeded ovary. 



Analysis of the Genera. 

 Calyx bell-form, regular, S-clefi. Stamens 12. Herbs with creeping, 



underground stems. Wild Ginger. Asa'sum, 1 



Calyx tubular, bent, irregular. Anthers 6. Shrubby, erect or .climbing, 



■with very odd flowers. BvrthmoH. Aeibtolo'ohia. 



ASAEUM. Wild Ginger. " , 



1 A Canadense. Canada W. Leaves in pairs, broad-renilbrm, with the single flower 



between the petioles scarcely above-ground. May-JuVy. c. 



2 A. Virginioum. Virginia W. Leaf solitary, round-ovate, cordate, the singleiower 



much shorter than the petiole. Sepals obtuse. Mts. Va. S. April. 

 8 A. arifol'inm. Arum-lv. W. Leaf solitary, broadly hastate, with long, angular 

 lobes at base. Calyx throat contracted, lobes very short. Va. S. April. 



Order CI.— NYOTAGINACE^. Marvelworts, 



Herts (shrubs or trees) with swelling joints ; entire, opposite leaves ; 

 flowers surrounded by an involucre (which is, of course, calyx-like when 



the flower is*solitary) : 

 calyx often colored like a coroUa, tubular or funnel-form, breaking, off 



above the l-oeUed, l-seeded ovary. 



