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BOTANICAL EXPLORATION IN VENEZUELA - I 233
along stream above Laguna Mucubaji towards Laguna Negra, above
Los Apartaderos, state of Merfda, alt. 3625-3655 ra., July 21, 1944,
Julian A Steyermark 57487.
Also referred to this form are the following Colombian collections:
moist gully, bushy lower mountain slope, San Cristobal, Bogota,
Dept. of Cundinamarca, alt. 2700-2800 m., September 30, 1917, F. W.
Pennell 2326; hierba reptante, acuatico semis umergida, verde clara,
pecalos amarillos, cabeceras del rio Otun, bajando del Nevado de
Santa Isabel, paramos de la Laguna del Mosquito, Cordillera Central,
Dept. Caldas, alt. 3820 m., November 26, 1946, Cuatrecasas 23250.
Typical R nubigenus H.B.K. was described (ex DC. Syst. 1: 253.
1818) as having leaves "suborbiculatis 7-dentatis", scapes "apice
pubescente" and later (Nov. Gen. 5: 42. 1821) as having stems
"superne puberuli" and petioles "pubescente", while in the latter
publication the leaves are described as "5-7-crenata". Various
collections from Ecuador, Colombia, and Venezuela have the appressed
pubescence, especially on the petioles, base of the stems,
sheaths, and upper part of the peduncles, characteristic of typical
K. nubigenus. The leaves may vary in shape from suborbicular to
ovate, and from shallowly to prominently 5-9-crenate.
In forma subintegrus the blades of the leaves are often much larger
and only obscurely crenulate to subentire. The appressed pubescence
in this form, while sometimes present, is frequently lacking so that
the plant is almost glabrous.
MAGNOLIACEAE
Magnolia ptaritepuiana Steyermark, sp. nov.
Arbor 10-13 m. alta; cortice albicanti vel pallido-cinereo; foliis
coriaceis vel chartaceo-coriaceis, subtus dense cinereo-tomentosis,
13-19 cm. longis, 9-15 cm. latis, late ovalis vel suborbicularibus,
basi obtusis, apice rotundatis, nervis lateralibus 8-10-jugis adscendentibus;
petiolis 1.2-1.7 cm. longis, in diametro 2-3.5 m., glabris vel
interdum novellis apice et parte superiori costae villosis; stipulis
undique glabris, marginibus ciliatis, 9 cm. longis, 7 mm. latis, subcoriaceis;
floribus odoratis; sepalis 3, oblanceolato-oblongis, cuneatis,
apice obtusis vel rotundatis, 4-4.5 cm. longis, 2 cm. latis; petalis
6, albidis, arcuato-adscendentibus, oblanceolatis, cuneatis, apice
subacutis vel obtusis, 4.2 cm. longis, 1.5-2 cm. latis; gynaeceo e
carpidiis glabris, stylis apice recurvatis.
Type in herb. Chi. Nat. Hist. Mus., collected on densely forested
steep south-facing slopes overlying sandstone, between "Cave
Rock" and base of high sandstone bluffs, Ptari-tepui, state of Bolivar,
alt. 2100-2285 m., October 30, 1944, Julian A. Ste Yermark 59547
(2 sheets), "tree 30-40 feet tall with whitish or pale gray bark; leaves;
coriaceous-chartaceous, deep green above, gray-scurfy below, paler
green below; petals white, arched-ascending; flowers fragrant".