[6][7] Of the approximately 50 genera and more than 1,000 species of Convolvulaceae, I. batatas is the only crop plant of major importance—some others are used locally (e.g., I. aquatica "kangkong" as a green vegetable), but many are poisonous.

The genus Ipomoea that contains the sweet potato also includes several garden flowers called morning glories, but that term is not usually extended to I. batatas.

The leaf blades are very variable, 5 to 13 cm (2 to 5 in) long, the shape is heart-, kidney- to egg-shaped, rounded or triangular and spear-shaped, the edge can be entire, toothed or often three to seven times lobed, cut or divided.

[citation needed] The hermaphrodite, five-fold and short-stalked flowers are single or few in stalked, zymous inflorescences that arise from the leaf axils and stand upright.

The edible tuberous root is long and tapered, with a smooth skin whose color ranges between yellow, orange, red, brown, purple, and beige.

[12] In Central America, domesticated sweet potatoes were present at least 5,000 years ago,[13] with the origin of I. batatas possibly between the Yucatán Peninsula of Mexico and the mouth of the Orinoco River in Venezuela.

[16] The oldest radiocarbon dating remains of the sweet potato known today were discovered in caves from the Chilca Canyon, in the south-central zone of Peru, and yield an age of 8080 ± 170 BC.

[17][18] The genome of cultivated sweet potatoes contains sequences of DNA from Agrobacterium (sensu lato; specifically, one related to Rhizobium rhizogenes), with genes actively expressed by the plants.

[19] Studies indicated that the sweet potato genome evolved over millennia, with eventual domestication of the crop taking advantage of natural genetic modifications.

[31] Some researchers, citing divergence time estimates, suggest that sweet potatoes might have been present in Polynesia thousands of years before humans arrived there.

[46] Kang P'il-ri and Yi Kwang-ryŏ embarked on a project to grow sweet potatoes in Seoul in 1766, using the knowledge of Japanese cultivators they learned in Tongnae starting in 1764.

[64] In New Zealand, the Māori varieties bore elongated tubers with white skin and a whitish flesh,[65] which points to pre-European cross-Pacific travel.

With care, early-maturing cultivars can be grown as an annual summer crop in warm temperate areas, such as the Eastern United States and China.

"Orange sweet potatoes (the most common type encountered in the US) received higher appearance liking scores compared with yellow or purple cultivars.

"[73] In the Southeastern U.S., sweet potatoes are traditionally cured to improve storage, flavor, and nutrition, and to allow wounds on the periderm of the harvested root to heal.

[85] The table below presents the relative performance of sweet potato (in column)[G] to other staple foods on a dry weight basis to account for their different water contents.

The tuber is often cooked before consumption as this increases its nutrition and digestibility, although the American colonists in the Southeast ate raw sweet potatoes as a staple food.

In Kenya, Rhoda Nungo of the home economics department of the Ministry of Agriculture has written a guide to using sweet potatoes in modern recipes.

In China, sweet potatoes, typically yellow cultivars, are baked in a large iron drum and sold as street food during winter.

[94] In some regions of India, sweet potato is roasted slowly over kitchen coals at night and eaten with some dressing, while the easier way in the south is simply boiling or pressure cooking before peeling, cubing and seasoning for a vegetable dish as part of the meal.

[95] In Sri Lanka, it is called bathala, and tubers are used mainly for breakfast (boiled sweet potato is commonly served with sambal or grated coconut) or as a supplementary curry dish for rice.

Young leaves and shoots (locally known as talbos ng kamote or camote tops) are eaten fresh in salads with shrimp paste (bagoong alamang) or fish sauce.

They can be cooked in vinegar and soy sauce and served with fried fish (a dish known as adobong talbos ng kamote), or with recipes such as sinigang.

[98] Sweet potatoes are also used in a variant of halo-halo called ginatan, where they are cooked in coconut milk and sugar and mixed with a variety of rootcrops, sago, jackfruit, and bilu-bilo (glutinous rice balls).

In Vietnamese cuisine sweet potatoes are known as khoai lang and they are commonly cooked with a sweetener such as corn syrup, honey, sugar, or molasses.

[110][111] Māori grew several varieties of small, yellow-skinned, finger-sized kūmara (with names including taputini,[112] taroamahoe, pehu, hutihuti, and rekamaroa[113]) that they had brought with them from east Polynesia.

Modern trials have shown that these smaller varieties were capable of producing well,[114] but when American whalers, sealers and trading vessels introduced larger cultivars in the early 19th century, they quickly predominated.

[115][116][117][118] Prior to 2021, archaeologists believed that the sweet potato failed to flourish in New Zealand south of Christchurch due to the colder climate, forcing Māori in those latitudes to become (along with the Moriori of the Chatham Islands) the only Polynesian people who subsisted solely on hunting and gathering.

However, a 2021 analysis of material excavated from a site near Dunedin, some 250 km (160 mi) further south, revealed that sweet potatoes were grown and stored there during the 15th century, before the industry was disrupted by factors speculated to be due to the Little Ice Age.

[140] Cuttings of sweet potato vine, either edible or ornamental cultivars, will rapidly form roots in water and will grow in it, indefinitely, in good lighting with a steady supply of nutrients.