MULFORD EXPLORATION OF THE AMAZON VALLEY 



209 



white, broad and thin, equalino- the sepals in length. Pistils 1 

 mm. loni;-, tlie very short, slightly recnrved style subterminal, at 

 the inner edge of the summit. 



On the margin of a lake near Reyes, 1000 feet, Rushy and 

 WMie, October 25, 1921 {no. 1540). 



This species grows in company with A. tenella Mart., and so 

 closely resembles it that some doubt existed at first as to their 

 representation of two species. 



Araceae 

 Xanthosoma syngoniifolia 



Stems, petioles, etc., scabrellate. Rhizome densely tul)er- 

 iferous, compact, bulbiform, about 4 cm. broad, the roots ema- 

 nating from its upper snrface. Basal sheaths several, 3 to 6 

 cm. long, triangular, acuminate and acute, rigid, finely many- 

 nerved. Petioles to 6 dm. long, erect, slender, gradually and 

 regularly broadening downward into a sheath. Leaf-blades thin 

 and membranaceous, trifoliolate, the middle lobe sessile, entire, 

 15 to 20 cm. long, 5 to 10 cm. broad, obovate with cuneate base 

 and very short-pointed acute summit, pale beneath, the venation 

 slender, reticulate, the principal secondaries about 8 or 10 on 

 each side, their ends imited by an undulating intramarginal line, 

 another similar but more slender line close to the margin ; lateral 

 leaflets on short unequal winged petiolules, of two leaflets, the 

 inner mostly sessile, the outer with a short petiole-like base, 

 occasionally bearing a small basal leaflet or lobe on the outer 

 side; segments all similar to the terminal, except that the outer 

 are successively smaller and indistinctly dentate. Peduncle soli- 

 tary (f), nearly as long as the leaves, slender, fleshy, distinctly 

 articulated above the middle, Avhere it is sharply deflexed, the 

 joint fissured and open on the inner side and glandular. Spathe 

 somewhat exceeding the spadix, convolute, at maturity straight, 

 15 cm. long, constricted at the summit of the lower third, which 

 is closed about the pistillate inflorescence, the edges Avidely over- 

 lapping; in its closed form, ovoid and a little broader than the 

 upper portion, which is 3.5 cm. broad, lanceolate or ovate, some- 

 what concave, acuminate, acute, thinner than the basal por- 

 tion, greenish -white. Spadix adnate to the spathe by the dor- 

 sum of its base, its pistillate lower portion about 2.5 cm. long, 

 about 1 cm. broad ; sterile portion a little longer, about half as 

 thick, scaly at the base, narrowed upward ; staminate portion 

 7 or 8 cm. long, nearly 1 cm. thick, narrowed at base and summit. 



