Saurian surprise: lizards pollinate South Africa's enigmatic hidden flower

Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the parent species, and barriers to reproduction will typically exist. There are two primary mechanisms, speciation with and without geographic isolation—allopatric and sympatric speciation, respectively.Allopatric SpeciationIn allopatric speciation, gene flow between two populations of the same species is prevented by a geographic barrier, like...

From Water to Land

The diverse plant life on Earth—consisting of nearly 400,000 species—can be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.

Seedless Vascular Plants Were the First Tall Plants on Earth

Flowers are the reproductive, seed-producing structures of angiosperms. Typically, flowers consist of sepals, petals, stamens, and carpels. Sepals and petals are the vegetative flower organs. Stamens and carpels are the reproductive organs.

Plants have a life cycle split between two multicellular stages: a haploid stage—with cells containing one set of chromosomes—and a diploid stage—with cells containing two sets of chromosomes. The haploid stage is the gamete-producing gametophyte, and the diploid stage is the spore-producing sporophyte.