The family encompasses about 6–11% of all seed plants.[4] The largest genera are Bulbophyllum (2,000 species), Epidendrum (1,500 species), Dendrobium (1,400 species) and Pleurothallis (1,000 species). It also includes Vanilla–the genus of the vanilla plant, the type genus Orchis, and many commonly cultivated plants such as Phalaenopsis and Cattleya. Moreover, since the introduction of tropical species into cultivation in the 19th century, horticulturists have produced more than 100,000 hybrids and cultivars.
Pollinators are often visually attracted by the shape and colours of the labellum. However, some Bulbophyllum species attract male fruit flies (Bactrocera spp.) solely via a floral chemical which simultaneously acts as a floral reward (e.g. methyl eugenol, raspberry ketone, or zingerone) to perform pollination.[8] The flowers may produce attractive odours. Although absent in most species, nectar may be produced in a spur of the labellum (8 in the illustration above), or on the point of the sepals, or in the septa of the ovary, the most typical position amongst the Asparagales.
Phalaenopsis – Phalaenopsis, otherwise known as the moth orchid, this is perhaps the most common of various orchid flowers you can buy in a general garden center. Moth orchids bloom once or twice a year, and each flower can last as long as three months with the proper care, and are the longest-lasting of orchid blooms. Moth orchids do well with warm temperatures in the house, in the upper 70’s on average.
Also known as the Moth orchid – which is much easier and less cumbersome to pronounce – this orchid is great for beginners because it is easy to grow and maintain. Appearing in lovely colors such as yellow, light pink, and spotted with burgundy, the Moth orchid blooms on and off throughout the year and can tolerate repotting efforts – again, making them a great plant for those who are new to planting flowers in their garden. They have long-lasting flowers and look great as an indoor plant, which are a few of the reasons why they are one of the most popular types of orchids.

^ Zhang, Guo-Qiang; Liu, Ke-Wei; Li, Zhen; Lohaus, Rolf; Hsiao, Yu-Yun; Niu, Shan-Ce; Wang, Jie-Yu; Lin, Yao-Cheng; Xu, Qing; Chen, Li-Jun; Yoshida, Kouki; Fujiwara, Sumire; Wang, Zhi-Wen; Zhang, Yong-Qiang; Mitsuda, Nobutaka; Wang, Meina; Liu, Guo-Hui; Pecoraro, Lorenzo; Huang, Hui-Xia; Xiao, Xin-Ju; Lin, Min; Wu, Xin-Yi; Wu, Wan-Lin; Chen, You-Yi; Chang, Song-Bin; Sakamoto, Shingo; Ohme-Takagi, Masaru; Yagi, Masafumi; Zeng, Si-Jin; et al. (2017). "The Apostasia genome and the evolution of orchids" (PDF). Nature. 549 (7672): 379–383. doi:10.1038/nature23897. PMID 28902843.

The complex mechanisms that orchids have evolved to achieve cross-pollination were investigated by Charles Darwin and described in Fertilisation of Orchids (1862). Orchids have developed highly specialized pollination systems, thus the chances of being pollinated are often scarce, so orchid flowers usually remain receptive for very long periods, rendering unpollinated flowers long-lasting in cultivation. Most orchids deliver pollen in a single mass. Each time pollination succeeds, thousands of ovules can be fertilized.
If your Catasetum orchid leaves begin to yellow and drop off, do not despair; this deciduous orchid loses its leaves naturally during winter dormancy. There is much variation in appearance between Catasetum species, but one feature they all have in common is the trait of producing male or female flowers, which bear little resemblance to each other. The male flowers have an anatomical trigger that forcefully ejects pollen onto visiting bees.
Epidendrum orchids are among the oldest genera in the orchid taxonomy. Originally, this genus included all epiphytic orchids. As knowledge of the different types of orchids expanded, the classification became much more refined; for example, there are now some terrestrial species in the Epidendrum genus, and a great many other species have been moved to other genera. Still, over 1000 Epidendrum species exist. They are usually easy to grow, and most have tall canelike pseudobulbs that lean all over the place and frequently produce keikis. Fun orchids!
The Coelogyne orchid genus gets a lot less attention than it deserves. The plants have beautiful, fragrant flowers, can tolerate drought and neglect, and rapidly develop into massive, impressive specimens. The best-known species come from the foothills of the Himalayas, where the elevation produces cool temperatures. The largest-flowered species in the genus, Coelogyne cristata, is one of these cool-growing types.
Most orchids are not heavy feeders. Many orchids bloom year after year with no fertilizer at all. During active growth, when new leaves are being produced, you may fertilize every other time you water at half the strength recommended on the fertilizer package. However, it's important to deliver water without fertilizer at least once a month to flush excess fertilizer salts from the bark mix and avoid fertilizer burn to the roots.