I can form no satisfactory theory how the four forms
of this plant originated.
Rhamnus lanceolatus.
This plant exists in the United States, as I am informed by Professor Asa Gray,
under two hermaphrodite forms. In the one, which may be called the short-styled,
the flowers are sub-solitary, and include a pistil about two-thirds or only half
as long as that in the other form; it has also shorter stigmas. The stamens are
of equal length in the two forms; but the anthers of the short-styled contain
rather less pollen, as far as I could judge from a few dried flowers. My son
compared the pollen-grains from the two forms, and those from the long-styled
flowers were to those from the short-styled, on an average from ten
measurements, as 10 to 9 in diameter; so that the two hermaphrodite forms of
this species resemble in this respect the two male forms of R. catharticus. The
long-styled form is not so common as the short-styled. The latter is said by Asa
Gray to be the more fruitful of the two, as might have been expected from its
appearing to produce less pollen, and from the grains being of smaller size; it
is therefore the more highly feminine of the two. The long-styled form produces
a greater number of flowers, which are clustered together instead of being sub-
solitary; they yield some fruit, but as just stated are less fruitful than the
other form, so that this form appears to be the more masculine of the two.
Pages:
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396