14 KEY TO THE GENERA OF MANHATTAN PLANTS. 



Order 19. ULMACEAE. 



Fruit 1-celled, 1-seeded, indehiscent, dry or fleshy. Trees. 



35. Ulmus. Membranaceous samara, winged all around. 



36. Celtis. Drupe globular, axillary, solitary or few. Calyx persis- 

 tent at base. Stone globular (ridged, 5 mm). 



Order 20. MORACEAE. 



Fruit an akene. Calyx inferior. 



37. Morns. Calyx fleshy. Fruit multiple, resembling a blackberry. 

 Trees. 



38. Humulus. Akene enclosed in the sac-like calyx ; sacs in an 

 oblong head ; bracts foliaceous. Herbaceous vine. 



39. Cannabis. Calyx of 1 sepal folded around the 2-edged akene, 

 sharp pointed ; bracts narrow. Herb. 



Order 21. URTICACEAE. 



Fruit an akene. Sepals inferior, usually persistent. Herbs. 



40. Urlica. Sepals 4, the two outer short and narrow, the inner 

 large and enclosing the flat, ovate akene. 



41. Urticastrum. Flowers in loose, terminal cymes. Sepals 4 (only 2 

 noticeable in fruit). Akene flat and very oblique, reflexed on the 

 broadly-winged pedicel. 



42. Aclicea. Sepals 3. (Three rudimentary stamens curved under the 

 ovate flattened akene, which they discharge at maturity by their elas- 

 ticity). 



43. Boehmena. Akene enclosed in the calyx. (Calyx continued above 

 the ovoid flattened akene as a thick wing. Fruit in dense spikes). 



44. Parietaria. Ovoid akene enclosed in the tubular, 4-lobed, nerved 

 calyx. In axillary-bracted clusters. 



Order 22. SANTALACEAE. 



45. Comandra. Fruit 1-celled, 1-seeded, indehiscent, drupaceous (but 

 dry). Calyx lobes 5, superior, persistent. Herb. 



Order 23. POLYGONACEAE. 



Akene lenticular or angled. Calyx inferior, persistent. Herbs 

 with sheathing stipules. 



46. Bumex. Akene 3-angled, 3 outer sepals reflexed, 3 inner erect, 

 enclosing the akene, often considerably enlarged 



47. Polygonum. Akene lenticular or 3-angled, usually enclosed by the 

 5-6 parted calyx. Sepals all erect. 



Order 24. CHENOPODIACEAE 



Fruit a 1-seeded utricle, usually enclosed by the inferior, persistent 

 calyx. No scarious bracts. Herbs. 



