nal home unknown. Widely cultivated and nat- 

 uralized in southern Florida, Bennuda, through- 

 out West Indies, from Mexico to Argentina and 

 Brazil, and in the Old World tropics. 



Other common names. — papay, pawpaw (Vir- 

 gin Islands) ; papaya (Spanish) ; fruta bomba 



(Cuba) ; melon zapote (Mexico) ; papayo calen- 

 tano (Colombia) ; lechosa, papaya (Venezuela) ; 

 papayo, mamon (Argentina) ; papaya, pawpaw, 

 papaw (United States, English) ; papaye, papa- 

 yer (French); papaya, papao, papay (Dutch 

 West Indies) ; mamao, mamoeiro (Brazil). 



CACTUS FAMILY (CACTACEAE) 



Key to the 2 species illustrated (Nos. 175-176) 



A. Branches columnar, with 7-11 ridges and grooves : fruits round, spineless — 175. Cephalocereus royenii. 

 AA. Branches flat, oblong joints or pads ; fruits pear-shaped, mostly spiny — 176. Opuntia ruiescens. 



175. Sebucan, dildo 



This tree cactus of dry areas is easily recognized 

 by: (1) stout erect gray-green columnar branches 

 2^4-4 inches in diameter with 7-11 ribs, or ridges, 

 and grooves between the branches and trunk, not 

 woody but soft and succulent; (2) absence of 

 leaves, but with many clusters of several spreading 

 needlelike yellow to gi^ay spines %-2i/4 inches in 

 length along the ribs; (3) greenish, whitish or 

 purplish-tinged, flowers 2 inches or more in length, 

 tubular and fle.shy with many sepals and petals, 

 borne singly and stalkless along ribs near apex; 

 and (4) rounded but much flattened edible red 

 berry up to 1 inch high and 2 inches in diameter, 

 the surface smooth and spineless. 



A branched cactus 6-20 feet tall with trunk 4-12 

 inches in diameter, commonly dividing at 1-2 feet 

 above the base into several branches. As twigs 

 and leaves are absent, there is no definite crown as 

 in other trees. The trunk is reddish brown, 

 smoothish except for rows of spines radiating in 

 clustei"S and with very thin bark. The surface of 

 the smooth grooves in the branches is covered with 

 a bloom at least when young. 



The spines are in clusters, several radiating out 

 from the central point of attachment (areole), 

 which also bears inconspicuous whitish hairs. 

 Near the rounded apex of branches the ribs bear 

 tufts of longer white hairs about li/i inches in 

 length, which are woolly and somewhat shaggy. 



The tubular fleshy flowers extend straight and 

 nearly horizontal, opening at night. The flower 

 has an inferior, smoothish, spineless rounded 

 ovary about i/^ inch long, 1-celled; a funnelform 

 greenish fleshy tube (hypanthium) with many 

 overlapping oblong, rounded or pointed, whitish 

 or purplish-tinged, fleshy sepals about % inch long 

 and with about 10 whitish narrow pointed petals 

 %-i/4 inch long within ; very many white stamens 

 Vi~V2 iiich long attached at the throat and base of 

 the tube ; and protruding white fleshy style almost 

 2 inches long with many narrow stigma lobes. 



Cephalocereus royenii (L.) Britton & Rose 



The ovary develops into the fruit, while the re- 

 maining flower parts shrivel and dry, remaining 

 attached. The flattened berry contains red juicy 

 flesh slightly sweet and edible and many small 

 shiny black seeds less than i/jg inch long. Probably 

 flowering irregularly through the year. 



The trunk is composed mostly of soft water- 

 storing tissues, light green near the surface and 

 yellowish within, juicy and slightly salty in taste. 

 The soft wood is a light brown fibrous cylinder 

 with large white rays. 



The tree cactus is remarkably well adapted to 

 very dry conditions. The root system is broad and 

 near the surface where water from light rains can 

 be absorbed rapidly. The bulk of the plant is 

 made up of water storage tissue, which retains 

 water absorbed after rains for use over long dry 

 periods. The surface area is greatly reduced 

 through absence of leaves, and loss of water to the 

 air (transpiration) is correspondingly checked. 

 The branches have a very thick skin which also 

 retards evaporation and, being green, at the same 

 time cari-y on the processes of food manufacture 

 ( photosynthesis ) , normally functions of the green 

 leaves. Further, the fonnidable spines protect 

 the juicy stems from animal life. 



Scattered in dry forest on plains and hills at 

 lower elevations in southern and southwestern 

 Puerto Rico and rare at Cape San Juan in the di-y 

 extreme northeastern corner. Also on Mona, 

 Desecheo, Icacos, Culebraj and Vieques. Through 

 Virgin Islands on St. Croix, St. Thomas, St. John, 

 Tortola, Vii'gin Gorda, Anegada, and probably 

 smaller islands. 



Public fokest. — Guanica. 



Range. — Mona, Puerto Rico and smaller adja- 

 cent islands, Virgin Islands, and St. Kitts and 

 Antigua in northern Lesser Antilles. 



Other common names. — pipe-organ cactus, 

 cactus (Virgin Islands). 



Botanical synonyms. — Cereus royenii (L.) 

 Mill., Pilocereus royenii (L.) Riimpl. 



376 



