Evolutionary history of plants foliage consisted of fern-like fronds, although they were not closely related to ferns. The oldest fossil evidence of seed plants is of Late Devonian age, and they appear to have evolved out of an earlier group known as the progymnosperms. These early seed plants ranged from trees to small, rambling shrubs; like most early progymnosperms, they were woody plants with fern-like foliage. They all bore ovules, but no cones, fruit or similar. While it is difficult to track the early evolution of seeds, the lineage of the seed ferns may be traced from the simple trimerophytes through homosporous Aneurophytes. This
Four Treasures of the Study ceramic stones (澄泥硯) which are manufactured by a process which is said to have been developed in Luoyang in Henan. Classical scholars had more than just the Four treasures in their studies. The other "Treasures" include the brush-holder (笔架), brush-hanger (笔挂), paperweights (镇纸), the brush-rinsing pot (笔洗), and the seal (圖章) and seal-ink (印泥). For painting, Chinese pigments are also used. Four Treasures of the Study Four Treasures of the Study, Four Jewels of the Study or Four Friends of the Study is an expression used to denote the brush, ink, paper and ink stone used in Chinese and other