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
On the Movements and Habits of Climbing Plants aim. This book stands second in line to his first work on plants, "On the various contrivances by which British and foreign orchids are fertilised by insects." (1862) This work is subdivided into chapters concentrating on a particular type of climber which he divided into four main classes but Darwin, in this volume, concentrates on the two main classes, the twining plants and the leaf climbers (divided into two sub-divisions: leaf climbers and tendril bearers) The following comprise the chapters: 1. Twining plants 2. Leaf climbers 3 & 4.Tendril bearers 5. Hook and Root climbers. Inspired by reading an 1858