282 NOTES ON THE GENUS YUCCA. 
Some importance has been attached to the number of leaves, which in healthy plants precede 
the development of the inflorescence, and there really is a relative difference in this respect in 
different species ; but specific characters could hardly be based on a condition which depends so 
much on external influences of soil, climate, etc. From Dr. Mellichamp’s notes it is evident that 
wild plants, in good health, exhibit a great many more leaves than cultivated ones, and that the 
number not rarely rises above one hundred on one axis. 
The diagnostic characters derived from the leaves must be adopted only with great circum- 
spection. The characters of the edges of the leaves are the most constant and reliable ones, 
though the abundance, thickness, and, still more, the length of the fibres, vary considerably, [25] 
even in forms of the same species. The shape of the leaf is quite variable, and more so still 
its color, its thickness, its stiffness (hence its direction), and the nature of its terminal spine; 
broader leaves with abundant parenchyma are apt to become plicate, while in the same species 
leaves of stronger fibrous structure are even. The characters derived from the roughness and the 
peculiar structure of the stomatic surroundings, as above detailed, are also inconstant, and therefore 
unreliable. 
INFLORESCENCE, 
The inflorescence, which terminates the axis in Yucca, usually consists of a compound raceme 
or panicle of different dimensions, from two to three or four feet high, with differently developed 
lateral branches, and therefore of different shape, oval, lanceolate, or pyramidal, and in one species 
at least (the northern form of Y. angustifolia) reduced to a simple raceme or spike. This inflores- 
eence is nearly sessile between the uppermost leaves, especially in the arborescent species; or it is 
raised on a longer or shorter scape, sometimes longer than the inflorescence itself, principally in the 
acaulescent forms. The scape bears reduced, bract-like leaves, those of the inflorescence itself 
usually becoming quite small and membranaceous, or, in some southern species, increasing in size, 
broad, concave and spathe-like, fleshy and discolored. The inflorescence is smooth or rough or pubes- 
cent, but no important value can be assigned to these differences. The pedicels are single or (on 
reduced branchlets) clustered, always distinct, but shorter than the flowers, curved, patulous, declined 
or pendulous, never, during the flowering period, erect. 
FLOWERS. 
The Yucca flower consists of a PERIGONE of six oval or lance-oval segments, united at base with 
one another, with the stamens and with the pistil, and not articulated, so that they wither after 
flowering without falling off. The perigone, expanding only for one evening and night, forms a 
shallow cup of whitish, cream-white or greenish-white color, sometimes externally tinged with pur- 
ple, of two to five inches in diameter; on the following morning, the fading segments conniv- 
ing, the flower assumes a globose or deep bell-shape, of one and one-fourth to three inches in [26] 
depth. The three outer segments are usually narrower and often a little shorter, and more fre- 
quently tinged with green or red along the midrib and tip; the three inner ones are broader (except 
apparently in Y. Guatemalensis, where they are narrower), more petaloid, of more delicate texture 
and color, and tipped with a small bunch of short white wool. They possess a certain, usually not 
pleasant fragrance. 
The size of the flower and even the shape of the segments is extremely variable in some of the 
species (Y. baceata, Y. Treculiana, Y. rupicola), and can scarcely be used for diagnostic purposes. 
4 The flowers of Y. canaliculata are described and figured in the Botanical Magazine as “ straw-yellow 
5 It is this day-time appearance which is almost always described and figured, and which gives an erroneous impression 
as to the form of the well-developed flower. 
