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Show 178 LOBELIA RAMOSA. CHAP. V. Plants of the Second GeneTation.-The above two lots of seeds wore p l ace d on damp S.a. nd ' and many of the cro. s.s e. d seed.· gormi· na t d tho last occasion before tho self-fort1hsed, and 0 ' as on . ' . ' . cr • were reJO· C t ed . Tl1roe or four pa1rs 1n .t he same state of berm. ma-t . planted on the opposite s1des of two pots ; a smglo lOll were ' . . 1 d pai· r I·l l a thn' 'd pot ,. and all the rema1n1ng seeds wore sown crowc o . : f th t ·nrhen the soedlincrs were about one and a half 111 a ·our po . vv o . I·l lC 1lO S I·U 11 e1· ght , they were equal on both s1des of tho throe first po t s; b u t I· n Pot IV ., in which they grew crowded and wore thus exposed to severe competition, the cro_ssod were about a third taller than tho self-fertilised. In this la~tor .1:ot, when the crossed averaged 5 inches in hoightJ the solf-fortih ·eel wore about 4 inches; nor did they look nearly such fino pla~ts. In all four pots the crossed plants flowered some clays before the self-fertilised. vVhon in full flower t~o tallest J_)lant on each side was measured ; but before this time the SI~glo cros~od plant in Pot III., which was taller than its antagom.·t, had ched and was not measured. So that only tho tallest plant on each side of three pots was measured, as in the following table:- TABLE LXIX. Lobelia ramosa (Second Generat-ion). Tallest•cros, ed Plant Tallest Self-fertilised No. of Pot. in"each Pot. Plant in each Pot. Inches. Inch es. I. 27 3 18g -- -- II. 21 19g --- IV. 21~ 19 Crowded. -- ·---- Total in inches. 70 57 The average height of tho throe tallest crossed r.lants is hero 23 · 33 and that of tho three tallest self-fertilised 19 Inches; or as 100 t; 81. Besides this difference in height, the crossed plants were much more vigorous and more branched than the selffertilised plants, and it is unfortunate that they wore not weighed. CHAP. v. LOBELIA FULGENS. 179 LOBELIA F ULGENS. This species offers a somewhat J.·orplexing case. In the first generation the self-fertilised plants, though few in number greatly exceeded tho crossed in height; whilst in the secon(l generation, when the trial was made on a much larger scale, th crossed beat the self-fertilised plants. As this species is generally propagated by off-sets, some seedlings were first raised, in order to have distinct plants. On one of these plants several flowers were fertilised with their own pollen; and as the pollen is rna ture and shod long before the stigma of the sam :flower is ready for fertilisation, it was necessary to number each flower and keep its pollen in paper with a corresponding number. By this moans well-matured pollen was used for self-fertilisation. Several flowers on the same plant were crossed with pollen from a distinct individual, and to obtain this the conjoined anthers of young flowers were roughly squeezed, and as it is naturally protruded very slowly by the growth of the pistil, it is probable that the pollen used by me was hardly mature, certainly le s mature than that employed for self-fertilisation. I did not at the time think of this source of error, but I now suspect that t~e growth of the crossed plants was thus injured. Anyhow the tnal was not perfectly fair. Opposed to tho belief that the pollen used in crossing was not in so good a state as that us ell for self-fertilisation, is the fact that a greater proportional numboJ' of the crossed than of the self-fertilised flowers produced capsules; but there was no marked difference in the amount of seed contained in the capsules of the two lots.* As the seeds obtained by the above two methods would not germinate when left on bare sand, they were sown on tho opposite ~ides of four pots ; but I succeeded in raising only a sm~l~ pair of seedlings of the same age in each pot. The selffertilised seedlings, when only a few inches in height, were in most of the pots taller than their opponents; and they flowered so much ear~ier in all the pots, that the height of tho flowerstems could be fairly compared only in Pots I. and II. .* Gartner has shown that cortat? plants of Lobelia julgens are quite sterile with pollen from the sam~ plant, though this pollen is effiCient on any other individual; · but none of the plants on whieh I experimented, which were kept in the greenhouse, were iu this peculiar condition. N 2 |
