1953] 



BOTANY OF THE GUAYANA HIGHLAND 



139 



obtusa, sparse ciliata, 1-nervia; flores 4-meri, solitarii, breviter pedunculati; 

 stamina isomorpha; antherae subulatae, connectivo infra apicem filamenti in cal- 

 car breve dorsale producto. 



Stems suffruticose, 5-20 cm. tall; internodes up to 3 cm. long, reddish, 

 glabrous except for a few minute sessile glands; nodes bearing 2 pairs of bristles 

 1-4 mm. long. Petioles slender, up to 4 mm. long, channeled above, reddish- 

 glandular. Blades isomorphic, ovate-lanceolate or elliptic, up to 25 rnm. long 

 and 10 mm. wide, obtuse, at base acute or somewhat cuneate, sparsely ciliate, 

 glabrous or very sparsely pilose above, glabrous and somewhat paler beneath, 

 1-nerved. Peduncles solitary, 1-flowered, 2 mm. long, strongly 3-angled, bearing 

 2 subulate bracteoles at the summit. Flower sessile, 4-merous. Hypanthium 

 obconic, 3.3 mm. long, 8-winged, each wing bearing 2 or 3 short cilia. Calyx- 

 tube 0.5 mm. long; sepals somewhat flaring, broadly depressed-semicircular, 

 much wider than long, very thin and minutely erose toward the summit. Stamens 

 isomorphic; filaments slender but flat; anthers subulate, 3.3 mm. long; thecae 

 straight, 2.4 mm. long; connective prolonged 0.4 mm. to the summit of the fil- 

 ament and below the filament into a straight retrorse spur about 0.5 mm. long. 



TYPE: cliffs in wet montane mossy forest, Phelps Camp to North Savanna, 

 Cerro Sipapo, Bassett Maguire & Louis Politi 27761; New York Botanical Garden. 

 Paratypes, Cerro Sipapo: Maguire & Politi 27504, 27538, 27620, 27621, and 27874. 

 The species is apparently well distributed on the mountain from the base of the 

 escarpment to the summit and was collected six times by Dr. Maguire. 



Macrocentrum glandulosum Gl. 



Flowers red, wet cliffs, Camp Savanna, Cerro Sipapo, alt. 4000 ft., Maguire 

 & Politi 27495; dry rocks, mixed woodland, base of escarpment, upper Camp 

 Savanna, 1350 m., Maguire & Politi 27666; moist rocks in mixed forest, north es- 

 carpment of Cerro Sipapo, alt. 1400 m., Maguire & Politi 27890; on rocks at 

 Culebra Peak, Cerro Duida, alt. about 1500 m., Maguire & Politi 29082, Maguire 

 & Politi 29103. Hitherto known from Cerro Duida. 



The fourteen species may be distinguished by the following key. 



Flowers solitary or rarely two in each inflorescence as it arises from the 

 base of a single leaf. 

 Stem scarcely developed; leaves crowded on short internodes; flowers 

 long-peduncled, held well above the leaves. 

 Leaves spatulate, long-tapering to the very short petiole, obtuse, pi- 

 lose on both sides. Al. droseroides Triana. 

 Leaves ovate-oblong, rounded at base, on distinct petioles up to 7 mm. 



long, glabrous beneath, pilose above. Al. parvulum GL 



Stem well developed, the leaves separated by distinct internodes; flow- 

 ers on pedicels only 1-3 mm. long. 

 Stem glabrous; sepals notably longer than wide, acuminate; flowers 5- 

 merous. 



Petioles 5-8 mm. long; leaves ovate-lanceolate, a third to a fourth as 



long as wide; delicate herb. Al. pusillum GL 



Petioles essentially lacking; leaves linear-elliptic to narrowly 

 oblanceolate, about a sixth as wide as long; low repeatedly 

 branched shrub. Al. angustifolium Gl. 



Stem with nodal setae; sepals depressed-semicircular; flowers 4-merous. 



Internodes hirsute on the angles. Al. minus GL 



Internodes glabrous. 



Stem and petioles sparsely beset with minute reddish glands; 



leaves thin, reddish beneath, up to 25 mm. long. Al. rubescens GL 



Stem and petioles glandless; leaves firm, green, up to 1 cm. long. 



Al. anychioides Gl. 



Flowers racemose 



Racemes essentially sessile; leaves spatulate to obovate, hirsute on both 



sides. Al. vestitum Sandw. 



