List of nitrogen-fixing-clade families



The nitrogen-fixing clade consists of four orders of flowering plants: Cucurbitales, Fabales, Fagales and Rosales. This subgroup of the rosids encompasses 28 families of trees, shrubs, vines and herbaceous perennials and annuals. The roots of many of the species host bacteria that fix nitrogen into compounds the plants can use.

The trees of this subgroup dominate many temperate forests. Cannabis, with the psychoactive drug tetrahydrocannabinol (THC), has been used recreationally and ceremonially for at least 2400 years, but was in cultivation at least 6000 years before that for its oils and for making fabric and rope. Cucumbers, melons and watermelons are cultivated around the globe. The Mediterranean diet around 6000 years ago included fava beans, lentils, chickpeas and other legumes. Chestnuts were spread throughout Europe by the ancient Romans. The apple (in the rose family) is the second-most-cultivated sweet fruit, after the grape (in the order Vitales, not in this clade).

Glossary
From the glossary of botanical terms:
 * annual: a plant species that completes its life cycle within a single year or growing season
 * basal: attached close to the base (of a plant or an evolutionary tree diagram)
 * climber: a vine that leans on, twines around or clings to other plants for vertical support
 * deciduous: falling seasonally, as with bark, leaves or petals
 * herbaceous: not woody; usually green and soft in texture
 * perennial: not an annual or biennial
 * succulent (adjective): juicy or fleshy
 * unisexual: of one sex; bearing only male or only female reproductive organs
 * woody: hard and lignified; not herbaceous

Fabales is basal within the nitrogen-fixing clade. This clade, the COM clade and the order Zygophyllales constitute the fabids under the fourth Angiosperm Phylogeny Group (APG IV) system.