I neglected to ascertain the number of seeds produced by perfect flowers exposed to the visits of insects, but I believe it is not greatly in excess of the above average. Mr. A.W. Bennett has carefully described the structure of the flowers of I. fulva in 'Journal of the Linnean Society' volume 13 Bot. 1872 page 147. This latter species is said to be sterile with its own pollen ('Gardeners' Chronicle' 1868 page 1286), and if so, it presents a remarkable contrast with I. barbigerum and noli-me-tangere.
Limnanthes douglasii (Geraniaceae).--Highly fertile.
Viscaria oculata (Caryophyllaceae).--Produces plenty of capsules with good seeds.
Stellaria media (Caryophyllaceae).--Covered-up and uncovered plants produced an equal number of capsules, and the seeds in both appeared equally numerous and good.
Beta vulgaris (Chenopodiaceae).--Highly self-fertile.
Vicia sativa (Leguminosae).--Protected and unprotected plants produced an equal number of pods and equally fine seeds. If there was any difference between the two lots, the covered-up plants were the most productive.
Vicia hirsuta.--This species bears the smallest flowers of any British leguminous plant. The result of covering up plants was exactly the same as in the last species.
Pisum sativum (Leguminosae).--Fully fertile.
Lathyrus odoratus (Leguminosae).--Fully fertile.
Lathyrus nissolia.--Fully fertile.
Lupinus luteus (Leguminosae).--Fairly productive.
Lupinus pilosus.--Produced plenty of pods.
Ononis minutissima (Leguminosae).--Twelve perfect flowers on a plant under a net were marked by threads, and produced eight pods, containing on an average 2.38 seeds. Pods produced by flowers visited by insects would probably have contained on an average 3.66 seeds, judging from the effects of artificial cross-fertilisation.
Phaseolus vulgaris (Leguminosae).--Quite fertile.
Trifolium arvense (Leguminosae).--The excessively small flowers are incessantly visited by hive and humble-bees. When insects were excluded the flower-heads seemed to produce as many and as fine seeds as the exposed heads.
Trifolium procumbens.--On one occasion covered-up plants seemed to yield as many seeds as the uncovered. On a second occasion sixty uncovered flower-heads yielded 9.1 grains weight of seeds, whilst sixty heads on protected plants yielded no less than 17.7 grains; so that these latter plants were much more productive; but this result I suppose was accidental. I have often watched this plant, and have never seen the flowers visited by insects; but I suspect that the flowers of this species, and more especially of Trifolium minus, are frequented by small nocturnal moths which, as I hear from Mr. Bond, haunt the smaller clovers.
Medicago lupulina (Leguminosae).--On account of the danger of losing the seeds, I was forced to gather the pods before they were quite ripe; 150 flower-heads on plants visited by bees yielded pods weighing 101 grains; whilst 150 heads on protected plants yielded pods weighing 77 grains. The inequality would probably have been greater if the mature seeds could have been all safely collected and compared. Ig. Urban (Keimung, Bluthen, etc., bei Medicago 1873) has described the means of fertilisation in this genus, as has the Reverend G. Henslow in the 'Journal of the Linnean Society Botany' volume 9 1866 pages 327 and 355.
Nicotiana tabacum (Solanaceae).--Fully self-fertile.
Ipomoea purpurea (Convolvulaceae).--Highly self-fertile.
Leptosiphon androsaceus (Polemoniacae).--Plants under a net produced a good many capsules.
Primula mollis (Primulaceae).--A non-dimorphic species, self-fertile: J. Scott, in 'Journal of the Linnean Society Botany' volume 8 1864 page 120.
Nolana prostrata (Nolanaceae).--Plants covered up in the greenhouse, yielded seeds by weight compared with uncovered plants, the flowers of which were visited by many bees, in the ratio of 100 to 61.
Ajuga reptans (Labiatae).--Set a good many seeds; but none of the stems under a net produced so many as several uncovered stems growing closely by.