Seed are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Different groups of plants have other modifications, the so-called stone fruits (such as the peach) have a hardened fruit layer (the endocarp) fused to and surrounding the actual seed. Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed, such as an acorn or hazelnut. Seeds are produced in several related groups of plants, and their manner of production distinguishes the angiosperms ("enclosed seeds") from the gymnosperms ("naked seeds"). Angiosperm seeds are produced in
Sub-provincial division Sub-provincial division A sub-provincial division () (or deputy-provincial divisions) in the People's Republic of China is like a prefecture-level city that is governed by a province, but is administered independently in regard to economy and law. Sub-provincial divisions, similar to prefectural-level divisions, an administrative unit comprising, typically, a main central urban area, and its much larger surrounding rural area containing many smaller cities, towns and villages. The mayor or chairman of a sub-provincial division is equal in status to a vice-governor of a province. Its status is below that of municipalities, which are independent and equivalent to provinces, but above