It was not so many years ago that practically nothing was known about the various plants which make up the forage crop on the National Forests. Forest officers could not identify the plants or say whether they were of value for forage or not. This made it difficult to secure the use of each range by the class of stock to which it was best adapted, to apply deferred and rotation grazing and to eliminate losses from poisonous plants. This obstacle to efficient range management was overcome when a system of plant collection and identification was started by the Forest Service. Some 23,000 specimens of about 3,000 different species have been collected on the National Forests, identified by specialists and the collector informed as to the value of each species. The identification of range plants is the first step toward securing an intimate knowledge of the life history of the plant. Such information as the soil and moisture requirements, date of flowering and seeding, requirements for reproduction, and its relation to other range plants is of the utmost importance if the maximum forage crop is to be produced on the range each year. This constitutes the latest stage in the development of grazing studies. [Illustration: Figure 31. Forest Ranger with his pack horses travelling over his district. Meadow Creek, foot of Mt. Wilson, Montezuma National Forest, Colorado] _Investigations Dealing with Poisonous Plants and Predatory Animals._ In coöperation with the Bureau of Plant Industry the study of poisonous plants and the means for reducing the losses from them has been undertaken. The death camas, the lupines, the larkspurs, some of the wild cherries, locoweed, and practically all species of zygadenus are plants that have been found to cause death among stock. While the handling of stock to avoid the poison areas can eliminate the losses to a small extent, it has been found that the most expeditious remedy is in digging out and destroying the poisonous plants. On the Stanislaus National Forest in California, a cattle range of about 14,000 acres, containing about 67 acres of larkspur, was cleared of this weed at a cost of about $695. The average loss of cattle in previous years had been about 34 head. Following the eradication of the larkspur the loss was 4 head. The net saving was valued at $1,800. Similar operations are conducted on other Forests.