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
Seeds of Diversity become prone to colony collapse disorder, which threatens the production of many insect-pollinated crops. Native bees are also in decline, which is partly due to loss of nesting sites in plant debris and in open untilled ground, and partly due to reduced diversity of food plants. Seeds of Diversity initiated a project called Pollination Canada with the aim of increasing awareness of native bees and alternative pollinating insects in order to protect them, so that farmers and urban gardeners can decrease their dependence on honey bees. Pollination Canada has 28 other partner organizations. In February 2013, Gretchen Bauta, Canadian philanthropist