48 



THE CACTACEAE. 



Type locality: High mountains of Bolivia. 

 Distribution: Known only from the type locality. 



This very strange plant is unknown to us except from the description and illustra- 

 tions, but it seems to be of this relationship. 



Illustrations: Bot. Zeit. 65 1 : pi. 2, f. 4, 10, as Echinocactus steinmannii. 

 Figure 60a is from a photograph of the illustrations cited above. 



DESCRIBED SPECIES, PERHAPS OF THIS GENUS. 



Echinopsis deminuta Weber, Bull. Mus. Hist. Nat. Paris 10: 386. 1904. 



Echinocactus deminutus Giirke, Monatsschr. Kakteenk. 16: 103. 1906. 



Plants globular to short-cylindric, 5 to 6 cm. high ; ribs 1 1 to 13, somewhat spiraled, more or less 

 tuberculate; spines numerous, somewhat rigid; flowers 3 cm. long, with a limb 3 cm. broad; outer 

 perianth-segments lanceolate, purple, 4 to 5 mm. long; inner perianth-segments 15, red to orange, 

 5 to 6 mm. long ; ovary bristly, 6 mm. in diameter ; stigma-lobes white. 



Type locality: Trancas, Argentina. 



Distribution: Known only from the type locality. 



We append the description of this plant to our genus Rebutia, to which it may belong, 

 but we have not been able to study any specimens of it. Weber's reference of the species 

 to Echinopsis certainly is erroneous, nor is it an Echinocactus in our understanding of that 

 genus. 



4. CHAMAECEREUS gen. nov. 



Plants small, usually creeping and forming little clumps, sometimes some of the joints pendent, 

 usually arising from the base, cylindric, with a few low ribs; spines acicular; flowers diurnal, soli- 

 tary at the areoles, comparatively small, erect; tube cylindric, bearing acute scales with hairy axils; 

 inner perianth-segments spreading, scarlet; stamens included; fruit small, globular, dry or nearly 

 so, bearing long woolly hairs; seeds black, opaque, punctate. 



Type species: Cereus silvestrii Spegazzini. 



Only one species is known, inhabiting 

 Argentina. 



We are indebted to Mr. Alwin Berger for 

 notes upon this interesting plant which have been 

 freely used in our description. 



The first part of the generic name is from x<*M a ' 

 on the ground, referring to the creeping or depressed 

 habit of the plant. 



1. Chamaecereus silvestrii (Spegazzini). 



Cereus silvestrii Spegazzini, Anal. Mus. Nac. Buenos 

 Aires III. 4: 483. 1905. 



Joints usually prostrate, sometimes 4 to 6 cm. high, 

 pale green; ribs about 6 to 9, but usually 8, low; spines 



soft, white; flowers orange-scarlet, about 7 cm. long, the axils of the scales bearing long black and 

 white hairs and a few bristles; flower-tube narrow, 2.5 to 3 cm. long; perianth-segments in 3 or 4 series, 

 spreading, 1 to 2 cm. long, 4 mm. broad, lanceolate, the outer ones acute, the inner shorter and 

 obtuse; filaments red to purple, short; style pale yellow to greenish white, longer than the stamens; 

 stigma-lobes 8 or 9, eonnivent. 



Type locality: Mountains between Tucuman and Salta, Argentina. 



Distribution: Tucuman, Argentina. 



This plant resembles in habit some of the creeping species of Echinocereus, but has 

 very different flowers; it has no close relatives in Argentina; it is largely grown in European 

 collections, where it is highly prized. Dr. Rose obtained specimens in Argentina in 191 5, 

 but so far none has flowered. 



FlG. 61. Chamaecereus silvestrii. 



