NOTES ON THE GENUS YUCCA. 279 
ponding to similar ones on the filaments, and entirely destitute of stigmatic functions; never did they 
contribute to the development of a pollen-grain occasionally adhering to them. Dr. Mellichamp’s 
notice of a minute drop of glutinous liquid in the tube formed by the coalescence of the so-called 
stigmas led me on to further experiments. That tube proved to be the real stigma, exuding 
stigmatic liquor, and insects (in these night-blooming flowers, of course, nocturnal insects) must be 
the agents which introduced the pollen into the tube. Last June, several forms of Yucca which 
were blooming under my windows, were carefully watched, and soon different species of beetles 
were found in the flowers, but not as regularly and frequently as white moths, which, usually in 
pairs, disported themselves in the open flowers at dusk, and were found quietly ensconced in them 
when closed in day-time.! The suspected insects were handed over to my friend, Mr. C. V. 
Riley, who thereupon took up the zodlogical part of the investigation, the surprisingly [20] 
interesting results of which are detailed by him in the succeeding paper. 
GERMINATION. 
The seeds of Yucca germinate easily, the cotyledon remaining partly in the ground? within the 
seed, extracting its liquefied contents, and never grows into a leaf organ; the first leaf issues from a 
slit in the cotyledon opposite the remnants of the seed; the saiseeding six or eight leaves of the 
first season following in } order, which, in the further growth of the plant, gradually changes to the 
higher orders of 3 and furiier From the nodes of the very short axis, stout white rootlets break 
through the bike of the leaves, the first one through the back of the cotyledon, opposite the first 
leaf, while the original radicle withers away. The Californian Y. Whipplei is the only one in which 
the axis, together with the base of the leaves, swells up into a sort of bulb. 
In the : second season, a stout, cylindrical secondary axis originates from the axil of one of the 
earliest of last year’s leaves, covered with scale-like leaf-radiments, and eventually producing from 
its nodes the rootlets which are to nourish the plant. This secondary axis takes a horizontal direc- 
tion in all the species I could examine, especially in the different forms of Y. filamentosa ; only in 
Y. angustifolia I have always found it to grow straight downwards, continuing this direction through 
at least the third and fourth year, and perhaps longer. Some observations seem to indicate that Y. 
gloriosa develops in a similar manner, The terminal bud of this secondary axis does not seem to 
form leaves as long as the primary leaf-bud continues to grow, and probably not until it has produced 
a flowering stem, and perhaps not even then for years. At last, however, the secondary axis branches 
out, if horizontal, near the surface of the soil, if perpendicular, as in Y. angustifolia, at a certain 
depth, even two or three feet, below it, forming horizontal branches, and eventually sending out 
leafy shoots above the surface. Some species are surrounded by such offshoots, thus forming clumps 
or thickets; Y. baccata, Y. gloriosa, Y. filamentosa, behave in this way, while Y. angustifolia is said 
to do this much more sparingly, and Y. alovfolia quite rarely. 
ROOTSTOCK. 
While the rootlets of Yucca annually spring from the youngest part of the rootstock, and [21] 
decay again after a season, the rootstock itself increases often to a large size and irregularly 
branched shape. We have very few data about the form of this organ; in fact, the only definite 
information accessible to me has been imparted by Mr. Lindheimer, hes with persistent zeal, has 
1 “These snow-white ‘millers,’ which I have found in al- the plants were found without fruit, or with fruit bearing 
most every flower examined, when closed in daytime, doubt- oer seeds. 
less enter their ‘ivory — at night, and would be quite 2 The very similar seeds of Agave have a very different 
sufficient for the purpose.” — Dr. MetiicnAmp. Later, the development ; in their germination the cotyledon grows into 
same correspondent agave s: “ Where I have found many moths a leaf, bearing the remnants of the seed on its tip 
last year, I noticed none or few this season. A few weeks later 
