Jennings: Contribution to Botany of Isle of Pines. 277 



Plant tissues with oil glands in leaves and involucral bracts; flowers small, in cymes. 



Pappus scales uniformly setiform 752. Pedis elongala. 



Pappus scales irregularly broadly scale-like to basally scale-like and upwardly 

 bristle-form 753. Pedis Swartziana. 



Tribe VI. Helianthe^. 

 Heads ladiate or discoid. Involucre usually not scarious. Receptacle chaffy 

 (none in Pinillosia and Heptanthiis). Anthers not caudate. Pappus never capil- 

 lary. 

 No chaff on receptacle. 



Pistillate flowers without corolla 734. Pinillosia Berlefii. 



Pistillate flowers with corolla. 



Leaf-blades glabrous above or merely puberulent. 



735. (Heptanthus cochlearifolius) . 



Leaf-blades pubescent on both suifaces 735. Heptanthus ranuncidoides. 



Chaff present on receptacle. 



Marginal flowers pistillate with tubular or obsolete corollas; disk-flowers perfect 

 but unfruitful. 



Heads with two kinds of flowers 738. Iva cheiranthifolia. 



Heads either all pistillate or all staminate 739. Ambrosia hispida. 



Ray-flowers fertile and ligdlate, disk-flowers sterile. 



Achene cj-lindric or angled 736. Acanthospermmn humile. 



Achene compressed parallel to the involucral scales. 



737. Parthenium Hysterophorus. 

 Disk-flowers fertile. 



Pappus consisting of scales or a crown of stiff retrorsely barbed bristles. 



Achenes not compressed, or, if so, laterally. 



Inner involucral scales enveloping the achenes of the ray-flowers. 



740. Enydra sessilis. 

 Inner involucral scales flat. 



Chaff awn-like 741. Edipta alba. 



Chaff broad, sometimes enclosing the flowers, but never the ripe 



fruit. 



Disk-achenes 4-s-angled, or rarely laterally compressed. 



Pappus obsolete 742. Isocarpha divaricata. 



Pappus consisting of a short irregul r or toothed crown. 



Ray-flowers pistillate, fertile. 



Shrubs with acutely 4-angled achenes. 



743. Borrichia arborescens. 



Herbaceous with achenes not at all or only obtusely 



angled 744. Wedelia trilobata. 



Ray-flowers unfertile or obsolete. 



745- Eleuther anther a ruderalis. 



Pappus of easily deciduous short, thin bristles. 



746. Melanthera angustifolia. 



Achenes strongly compressed parallel to the involucral scales. 



748. Bidens leiicantha. 



Pappus consisting of plumose bristles 749. Tridax procumbens. 



