EXPLANATION OF PLATES 



All of the figures, unless otherwise noted, are from herbarium ma- 

 terial, photographed in natural size by the author. Though it has not 

 been possible always to do so, an effort has been made to include in 

 each illustration the lower part of a basal internode so as to show the 

 presence or absence of cataphyls; and except for types of the older 

 species a representative specimen rather than a perfect one has been se- 

 lected for the photograph when possible. The upper figure of a plate 

 is designated by "a," and the lower by "6." Where no indication 

 is given, it is to be understood that the material figured is at the Mis- 

 souri Botenical Garden in St. Louis, or at the University of Illinois in 

 Urbana, the facilities of these institutions having been the main re- 

 source of the author in the preparation of manuscript. 



FRONTISPIECE. DISTRIBUTION MAP, showing the principal regions 

 indicated by the genus PJioradendron. 



North America: (1) Atlantic region, approximately that drained 

 by the Mississippi river and the eastern streams, occupied by PJiora- 

 dendron only south of the Ohio and Missouri rivers ; (2) Kocky Moun- 

 tain region, occupied by Phoradendron only in its southern part which 

 is scarcely more than a northern Chihuahuan extension; (3) Calif or- 

 nian region, reaching Oregon; (4) Sonoran or desert region, essen- 

 tially the valley of the lower Colorado river with the coasts and islands 

 of the gulf of Baja California; (5) Chihuahuan region, connecting 

 the Rocky Mountains with the eastern and western Sierra Madre 

 ranges of Mexico; (6) Mexican table-land, lying between the Sierra 

 Madre ranges and passing into the southern Chihuahuan region; (7) 

 Sierra Madre ranges, confluent into (8) the Cordilleran or Guatemalan 

 region, which itself passes into (9) the Isthmian or Costa Rican re- 

 gion, reaching from Costa Rica into coastwise Venezuela; (10) Yuca- 

 tecan region. 



South America : (11) Andean region, of great extent in the moun- 

 tains, meeting the Isthmian region in Venezuela; (12) Bolivian re- 

 gion, comprising the uplands of southwestern Bolivia and northwest- 

 ern Argentina; (13) La Plata region, no Phoradendron known from 

 south of Uruguay; (14) Brazilian upland or southern Brazilian re- 

 gion, limited in general by the valleys of the Amazon and Paraguay 

 rivers; (15) Amazonian region; (16) Cayenne region, lying between 



163 



