THE GARDENERS' MONTHLY 



[January, 



paper by Robert Ridgvvay in the " Proceedings of 

 the National Museum," wherein he shows that the 

 forest area of the Wabash basin has extended to 

 such an extent that numerous small grassy prairies, 

 which were common at the first settlement of the 

 country, have become transformed to woodland, 

 and that, owing to this encroachment, the forest 

 area of the valley is greater than it was fifty 

 years ago. There are now huge trees of oak and 

 hickory, eighty feet high, on what certainly was 

 grassy prairies fifty years ago. The question of the 

 origin of these prairies being definitely settled, the 

 anthropological one connected with it derives a 

 new interest. As the natural condition of the North 

 American continent is to be covered by a forest 

 growth and this forest growth has been kept down 

 by the agency of annual Indian fires, the Indians 

 must have been here before the subsidence of the 

 waters which covered the prairies, and the annual 

 fires following the regular subsidence alone kept 

 the forests from springing up. It is an excellent 

 illustration of the fact that the settling positively 

 of one important question only leads to the intro- 

 duction of other and often greater ones. — Inde- 

 pendent. 



Temperatike and Hardiness. — We ha\ e often 

 called our readers' attention to the fact that the 

 hardiness of plants does not depend on temperature 

 alone. An evergreen will endure a much lower 

 temperature in England than it will in America, 

 while a deciduous tree, killed by a few degrees of 

 frost in England will endure zero in America. In 

 our climate one of the most delightful of very 

 hardy shrubs is Callicarpe purpurea. We have 

 known it to endure iS*- below zero, and how much 

 more we do not know. In contrast with this we 

 have the following from the London GardeJi : " In 

 one of the houses in Messrs. Veitch's nursery there 

 is a fine specimen of this old, but uncommon plant, 

 with its long, slender shoots completely wreathed 

 with dense clusters of bright purple berries, a little 

 larger than gun shot. We have hitherto seen this 

 plant grown in a greenhouse, but here it has been 

 grown with great success in a warm and moist 

 house. We have never seen a finer example, and 

 it well shows what a beautiful plant it is when 

 grown well. It will retain its berries throughout 

 the winter, and will be highly ornamental. 



Foretelling the Weather by the White 

 Pine. — The Illustrirte Garten-Zeitung, of Vienna, 

 Austria, says it is the easiest thing in the world to 

 foretell the weather by observing the common 

 American white pine — Pinus strobus. If we are 



to expect rain or snow within a reasonably short 

 space of time, the branches of the last two seasons* 

 growth will be pendulous. If such weather be a 

 long way off, the branches will be i-aised rather 

 than drooping. 



Colored Flowers in the Carrot. — At a 

 recent meeting of the Academy of Natural Sciences 

 of Philadelphia, Mr. Thomas Meehan remarked 

 that the umbellule of colored flowers in the center 

 of the umbel of the carrot, was represented as 

 usually fertile in Europe and sterile in the United 

 States. He had always found them sterile in the 

 United States until this season, when he discovered 

 that those in the center of the first umbel of the 

 season were fertile. Those in the umbels from 

 lateral shoots were sterile. This had no doubt 

 always been the case, the laterals probably being 

 the only ones examined in former investigations. 



Progress of Plant Knowledge. — Hippo- 

 crates described 234 species, Theophrastus fol- 

 lowed with 500. Pliny knew, as well as can be 

 made ojjt now, 800. Tonmefort, at the beginning 

 of the last century, described 10,146. Many of 

 these had to be united as not distinct enough for 

 modern science, till at the death of Linnajus 7,294 

 had been described. De Candolle, in the Theory 

 of Elementary Botany, made 30,000 named species. 

 Lindley, in 1853, gave the number as 92,920. Now, 

 in the neighborhood of 150,000 species are known, 

 with possibly an equal number not yet known. 

 Thus figures the Revue de r horticulture Beige. 



The Relation df Heat to the Sexes ok 

 Flowers was discussed before the Philadelphia 

 Academy of Natural Sciences last year, as noted at 

 the time in these columns, and the important princi- 

 ple developed that it takes less heat to bring forth a 

 male flower, or the male parts of a flower, than it does 

 in the case of the female. This explanation is being 

 found the key to much that was supposed to be 

 among the " unknowables " before. In Europe, 

 or at least, the northern portion of it, where the 

 winter temperature is low till the spring actually 

 arrives, the male flowers, or organs of plants, re- 

 main inactive till the weather is warm enough to 

 bring forward the females also, when they receive 

 the necessary pollination requisite for fruitfulness. 

 In other countries, where there are occasionally 

 warm days or warm periods, the male flowers in 

 monoecious or diaecious plants are brought forward 

 to maturity, while the females, desiring a still 

 warmer temperature, linger behind. As a result, 

 some trees, like hazelnuts and walnuts, which pro- 

 duce regularly crops of nuts in some countries, be- 



