This section is from the book "The Gardener's Monthly And Horticulturist V18", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
Our European friends are finding some curious " facts " in regard to rainfall and forests. In France, a Mr. Fautral found that there was much more rain fell in a forest than on a sandy plain not a great way from it. It so happened, however, that another forester kept an account in a forest about the same distance from the sandy plain, and the figures from the two forests do not agree. Most persons would have suspected an error in ascribing much influence to the forests, but these two fell to discussing the nature of the forests themselves; and now it is asked of us to believe, that while ten per cent, more rain will fall on a pine forest than on a sandy plain, only five per cent. more falls on an oak one! The only wonder is that 95 per cent, should fall on the treeless plain.
On the Diurnal Opening of Flowers. At a recent meeting of the Academy of Natural Sciences of Philadelphia, Mr. Thomas Meehan referred to observations he had made this season on the nocturnal and diurnal expansion of flowers, and said that, contrary to the popular impression, it was not probable that light or its absence alone determined the opening of the blossoms. There were some plants, as for instance Cenothera biennis, the Evening Primrose; Anagal-lis arvensis, the "Pimpernel," and others which remained open or otherwise longer when the weather was humid or clear, and were looked on in consequence as kinds of floral barometers; but from other facts it was clear that it was not the weather merely, but some other incident accompanying the weather that governed the case.
For instance, though Cenothera biennis, and other Cenotheras opened at evening, - and if the atmosphere be moist, would continue open the greater part of next day. - many species opened only in the day time, and this they did regularly quite regardless of meteorological conditions. CE. serrata, of Colorado, was one of these. It was regular in opening about noon, and the blossoms were all closed long before sundown.
In other allied families, we saw similar divergencies. In the Cactus family, Opuntia and Mammillaria opened only about mid-day; while most of the Cereus opened at night. The night-blooming Cactus was a familiar example. But the chief interest was in the fact that many had their special hours of day or night for the expansion. The Portulacca oleracea, common Purslane, opened about eight A. m., and by nine had performed all its functions; while a closely-allied plant, the Talinum teretifolium, from the serpentine rocks of Chester County, opened at one P. M., and was closed by three. The conditions of the weather did not seem to influence them.
There was the same attention to daily periods in the growth of the parts of plants, as well as in the expansion of the petals. In composite plants, the floral growth was generally in the morning, and was usually all over by nine or ten o'clock A. m. The elongation and expansion of the corolla was usually completed in an hour after sunrise; but the stamens grew for an hour more, and the pistil continued for still another. There was little if any growth in the floral parts after nine o'clock in a very large portion of this order of plants. In grasses, Cyperaceae, and some rushes, the floral parts were very exact in their time of opening. In the Plantains (Plantago) the pistils appeared a day or more in advance of the stamens, and these last appeared at about a regular time in each day. In Luzula campestris, the wood form, he had by a series of observations timed it exactly. Before nine the anthers were perfect, but by ten the pollen has been all committed to the winds, and only dried membraneous matter remained.
So far as he could ascertain, meteorological conditions did not influence the time in the least in this case.
The popular impression of light and moisture, as agents in this behaviour, had seemed to receive a tacit scientific assent. It was clear he thought there was 'a more powerful agency underlying these, and it was perhaps a gain to science to be able to see this, though in so dim a light.