How do the seeds of ephemerals “know” when it is time to germinate? Experiments have revealed that the seeds of annuals will germinate only when enough water percolates through the soil to dissolve away a “growth inhibitor” in their coats. A single light rain will not do the job. In this way premature sprouting into a too-dry environment is prevented. The winter annuals, furthermore, will only germinate when soils are cool, and the summer annuals when soils are warm. These finely tuned adaptations thus allow plantlife to take full advantage of favorable seasons in the desert. Early spring ephemerals climax their show in March. From late February to mid-April they are completing their growth and putting forth the precious seeds that will assure survival for the next generation. At the head of this parade of flowers in the monument is a purple-blossomed immigrant from the Mediterranean, the now thoroughly naturalized FILAREE. In addition to the small purple flowers, which may appear as early as January, the conspicuous “tailed” fruits almost always attract attention. When dry, they are tightly twisted, corkscrewlike; when damp they uncoil, forcing the needle-tipped seeds into the soil. [Illustration: Desert-marigold.] INDIAN WHEAT is one of the first plants to lay a green carpet over the sandy desert floor in spring. The tan, individual flower heads are conspicuous, but their numerous, close-growing spikes form a thick, luxuriant, pilelike ground cover. The countless tiny seeds are eagerly sought each spring by coveys of Gambel’s quail, and are also harvested by Pima and Papago Indians. DESERT CHICORY is somewhat like the common yellow dandelion but is longer stemmed and less coarse. Its white or butter-yellow blossoms make it one of the noticeable spring annuals in the desert. It rarely grows in pure stands but appears in conspicuous clumps among other short-lived plants. Somewhat similar in appearance to desert chicory is WHITE TACKSTEM, one of the handsomest of the spring quickies. It is usually found on dry, rocky hillsides and has white or rose-colored flowers. Its name is derived from the presence of small glands which protrude in the manner of tiny tacks partially driven into the stems. Following abnormally wet winters, FIDDLENECK covers patches of sandy or gravelly soil with a dense growth of bristly erect plants. These bear tight clusters of small yellow-orange blossoms arranged along a curling flower stem resembling the scroll end of a violin, hence the name. This plant, favored by the same growing conditions as creosotebush, frequently forms a dense though short-lived growth around the bases of those shrubs.