16. Platygonus, Otto

At first upright, later somewhat reclining, branching, at the base about 1 in. diam., tapering in the new growth: ribs 8, low, arched: areoles about 1/4in. apart, very small, yellow, becoming gray, subtruded by a small 3-angled bract: radial spines 12-15, spreading, bristle form, little more than 1/8in. long; central solitary, slightly longer and stronger; all the spines at first yellow-brown, changing to white or gray with age.

17. Caerulescens, Salm-Dyck (C. Landbeckii, Phil.)

Arborescent or shrubby, 3-5 ft. high: stems 1-1 1/2 in. diam.: ribs usually 8, obtuse: areoles approximate, white bud soon becoming black: spines rigid; radials 9-12, 1/4-1/2in. long, black; centrals 4, 3/4in. long, stronger, black or white: flowers from the side of the stem, slightly curved, 6-8 in. long by 6 in. diam., tube bronze-green, corolla white or occasionally rose-pink: fruits ellipsoidal, pointed at both ends, about 3 in. long and half that in diam., bright red, with blue glaucous covering. Argentina. B.M. 3922.

18. Bridgesii, Salm-Dyck

Upright, tall, columnar, simple or later branching at the base, bright green when young, becoming blue to gray-green, 1 1/2-2 in. diam.: ribs 5-7, very broad and low: areoles 1/2-3/4in. apart, yellowish to gray: spines 3-5, radiating, the under one, or seldom the upper one, the longest, 1 1/2 in. long, stiff, sharp, straight, dark honey-yellow, with brown tips, becoming gray with age. Bolivia.

Variety lageniformis, K. Schum. (C. lageniformis, Forst.). Spines more numerous, somewhat longer.

19. Azureus, Parm. (C. Seidelii, Lehm.)

stem upright, tall, slender, columnar, branching from the base, in the young, fresh bluish green, later dark green with gray, glaucous covering, about 3-4 ft. high and about 1 in. diam.: ribs 5-7, rounded, enlarged at the areole: areoles about 3/4-1 ft. apart, elevated, large, abundantly woolly when young: spines 8-18, nearly alike, about 1/8-3/8in. long, stiff, slender, needle-form to bristle-like, black; the 2-4 central ones somewhat longer: flowers 8-12 in. long, obliquely attached to the stem, slightly curved, white. Brazil.

20. Csesius, Otto

Upright, columnar, branching at the base, somewhat tapering above; in new growth, beautiful light blue, pruinose; later, light green to slightly bluish, about 1 1/2 in. diam.: ribs 5-6, separated by sharp grooves, about 1/2in. high, compressed, faintly crenate, becoming depressed in older growth: areoles about 3/8in. apart, small, yellow at first, later becoming white and finally gray: radial spines 8-10, sometimes more appear later; radiate, light amber-color, brown at the base, the lower pair the longest, mostly about 1/2in. long; centrals 4-7, like the radials but usually somewhat stronger, longer and darker; all the spines thin, needle-form, flexible, sharp; later, fight, horn-color, finally gray. S. Amer.(?).

aaa. stems weak, clambering over rocks or other plants, and without aerial roots.

21. Bonplandii, Parm

stems at first upright, later clambering over rocks and bushes, about 1-1 1/2 in. diam., branching and spreading, in new growth commonly of a bluish or purplish green, later gray-green: ribs 4-6, sharp, compressed, crenate, separated by broad, concave faces; later the ribs become much depressed, so that the stem is sometimes nearly cylindrical; the ribs commonly run spirally around the axis of the stem: areoles 1/2-1 1/2in. apart, at first considerably depressed, later shallower, white, becoming gray: radial spines 4-6 (later 1-4 more appear), straight, spreading, the largest about 1/2-1 in., stout, subulate, pointed, the under one needle-form and shorter; central solitary, straight, stronger, 1 in. long, deflexed or porrect; the stronger spines are white, with tips and bases brown, when young beautiful ruby-red, later all are gray, with black tips and bulbous bases: flowers from the lateral areoles about 10 in. long, white, nocturnal: fruit nearly spherical, about 2 in. diam., mammate, dark carmine-red. Paraguay, Brazil, and Argentina.

22. Tortuosus, Forbes

(C. atropurpureus, Haage). stems slender, weak, at first upright, but later reflexed, reaching a length of 3-4 ft., and 1-1 1/2 in. diam.: ribs commonly 7, sometimes but 5, rounded, low, separated by regular serpentine grooves: areoles about 1 in. apart, large: radial spines 5-8, about 3/8-1 in. long; centrals 1-4, about 3/4-1 1/2 in. long; all the spines slender, rigid, red-brown when young, becoming ashy with age: flowers from the previous year's growth, about 6 in. long, trumpet-shaped, tube olive-green and spiny, in the axils of the reddish green scales; outer petals pale green, tinted with brown; inner petals clear white: fruit spherical, brilliant red without and white within, mammate, bearing a few spines on the summits of the lower mammas. Argentina.

23. Martinii, Labour

(C. monacanthus, Hort.). At first upright, later requiring a support; freely branching from the base, branches long, reaching nearly 5 ft., 3/4-l in. diam., slightly tapering, dark green: ribs 5-6, separated by serpentine grooves, contracted between the areoles; sometimes the ribs are not evident, when the stem is cylindrical: areoles about 1-1 1/2 in. apart, white: radial spines 5-7, reddish, short, bristle-form, with bulbous bases or short conical, usually about 1/8in. long; central solitary, mostly deflexed, 1/2-1 in. long (in young growth, frequently not longer than the radial), subulate, robust, light brown or white, with bases and tips black: flowers from the older growth stems, 8-9 in. long, clear white, nocturnal: fruit spherical (very similar to C. tortuosus), pointed, dark carmine-red, about 2 in. diam., mammate, a few spines on the mammas, toward the base of the fruit Argentina. R.H. 1860, pp. 658-9. - This species is commonly sold under the name of C. platygonus.

24. Pitajaya, Dc

(C. pernambucensis [fernambu-censis], Lem. C. formosus, Salm-Dyck. C. variabilis, Pfeiff.). By recent authorities referred to the genus Acanthocereus. stem at first simple, later branching, in young growth light green, turning grayish green with age, pointed, 3/4-1 1/4 in. diam.: ribs 3-5, commonly 4: areoles about 1 in. apart, large, bearing a conspicuous amount of curly hair, about 1/2in. long, in new growth: radial spines 5-7 and a solitary central one, uniform, about 3/8-5/8 in. long, amber color to brown and finally gray: flowers from the older growth, large, about 8 in. long, slightly curved, white, nocturnal. Uruguay, Brazil, Colombia. B.M. 4084. - C. grandis, Haw., according to Weber, is but a larger form of this species.

aaaa. stems more or less climbing by means of aerial roots.

25. Martianus, Zucc

Of bushy growth, branching, reaching a height of 3 ft. and more: branches slender, provided here and there with aerial roots, cylindrical, about 3/4in. diam.: ribs commonly 8, straight, separated by sharp grooves, very low: areoles 1/4-3/8in. apart, small, white: radial spines 6-10, bristle-form, spreading, clear honey-yellow, at base brownish, later whitish and becoming gray, about 1/4in. long; centrals 3-4, similar, only somewhat stouter and darker: flowers usually abundant, straight or slightly S-shaped, 4-5 in. long, scarlet-red: fruit spherical, reddish green, covered with bristles. S. Mex. B.M. 3768.

C. ventimiglia, Vaupel (Borzicactus ventimiglia, Riccob.). stem slender, 8- or 9-ribbed: spines in clusters of 8-10, spreading: perianth-tube elongated, opening into a large throat; petals red-violet: fruit small, globular, bearing few bracts. This species apparently does not belong to the true Cereus, and is probably much nearer Cleistocactus, as suggested in the Kew Bulletin. It was described from plants flowering in the Botanical Garden at Palermo, Italy, and which are said to have come from Ecuador. Borzicactus is a recently described genus, not yet introduced into American collections.

C. alamosensis=Rathbunia alamosensis. - C. Baumannii= Cleistocactus Baumannii. - C. Berlandieri = Echinocereus. - C. caespitosus = Echinocereus. - C. candelabrum = Lemaireocereua Weberi. - C. Chiotilla=Escontria Chiotilla. - C. chloranthus=Echi-nocereus. - C. coccineus=Echinocereus. - C. Cochal=Myrtillocactus Cochal. - C. conoideus=Echinocereus. - C. ctenoides=Echinocer-eus. - C. cylindricus=Opuntia.. - C. dasyacanthus = Echinocereus. - C. Donkelaeri=Selemcereus Donkelaerii. - C. dubius= Echinocereus. - C. Dumortieri=Lemaireocereus Dumortieri. - C. eburneus=Lemaireocereus griseus. - C. Emoryi=Bergerocactus Emoryi. - C. Engelmanii='Ech'mocercus. - C. enneacanthus = Echinocereus. - C. eruca=Lemaireocereus eruca. - C. extensus=Hylo-cereus extensus. - C. Fendleri=Echinocereus. - C. flagelliformis= Aporocactus flagelliformis. - C. geometrizans = Myrtillocactus geometrizans. - C. giganteus=Ca.megiea. gigantea. - C. gonacdnthus =Echinocereus. - C. grandiflorus=SeleniceTeus grandiflorus. - C. Greggii=Pemocereua Greggii. - C. gummosus=Lemaireocereus gummosus. - C. Aamatus=Selenicereus hamatus. - C. inermia= Selenicereus inermis. - C. longisitus=EchinoceTeua. - C. Mal-lisonii is a hybrid. - C. MacDonaldiae=Selenicereus MacDonaldiae. -C. marginatus=Pachycereus marginatus. - C. Maynardii= Selenicereus. - C. mexicanus is probably a hybrid. - C. mojavensis =Echinocereus. - -C. napolednis=Hy\ocereus napoleonis. - C. Nickelsii=Cephalocereus. - C. nycticalus=Selenicereus nycticalus. -C. paucispinus=Echinoeereus. - C. pechtinatus=Echinocereus.

- C. phoreniceus = Echinocereus. - C. princeps = Acanthocereus pentagonus. - C. procitmbens=Echinocereus. - C. gueretarensis =Pachycereus queretarensis. - C. Regelii-SelemceTeus hybrid. -C. repandus= Harrisia gracilis. - C. .Raetteri=Echinocereus.

- C. Schieeri = Echinocereus. - C. senilis = Cephalocereus. - C. serpentinus=Nyctocereus serpentinus. - C. specidsus=Heliocereus. speciosus. - C. spinulosus=Selenicereus spinulosus. - C. stelldtus =Lemaireocereus stellatus. - C. stramineus=Echinocereus. - C. Thurberi = Lemaireocereus Thurberi. - C. triangularis = Hylo-cereus tricostatus. - C. tuberosus = Wilcoxia. - C. viridiflorus. - Echinocereus. J. N. RoSE.†