Ipomoea batatas and cultivars.
Sweet Potato, in Family Convolvulaceae is part of the Batatas section of the Ipomoea genus.
The complex has around 12 species including I. gracilis, I. lacunosa, I. littoralis, I. tiliacea, and I. triloba.
Sweet Potatoes are herbaceous perennial plants with stems mostly around 4 to 8 m long.
Stems can be prostrate or climb by twining.
The occasionally branching stems have a white sap and may root at the nodes.
Some of the fibrous roots form large fleshy tubers whose features vary with the cultivar.
The skin, and the flesh can be yellow, orange, white, purple, brown or red.
The alternately arranged leaves, on a petiole up to 30 cm long are in a spiral.
The blades, up to around 14 cm long and 12 cm wide are very variable in shape.
The basic outline is ovate, almost round or heart-shaped (cordate).
The edge may be smooth, have teeth or 3 to 5 (7) shallow to deep lobes.
The base can be heart-shaped or flat and the leaf/lobe tip/s can be blunt or pointed.
Depending on the cultivar the leaves are green or purplish and they usually have no hairs.
Two swollen areas at the top of the petiole contain complex nectaries.
Each has a small cavity lined by multi-cellular hairs.
Each hair or trichome has a basal cell and a stalk cell holding up to 9 secretory cells.
Erect axillary inflorescences, on a short stalk or peduncle have 1 to a few stalked flowers.
The 5 pointed sepals are in 2 whorls with the inner 3 being slightly larger at up to 1.5 cm long.
They usually have fine hairs on the outer surface and longer ones around the edge.
The 5 petals are fused into a tube up to 7 cm long and a funnel-shaped top or limb.
The limb has shallow lobes and mid petaline bands ending in a short point or mucro.
The corolla can be white with a purple throat or lavender with a deeper throat.
The 5 stamens, of unequal lengths insert near the bottom of the corolla tube.
There are glandular hairs on the base of the filaments.
The lobed nectary disc around the base of the ovary is orange.
The ovary has 2 locules each with 2 ovules and a style with a bi-lobed stigma.
The fruit are capsules around 6 mm long with up to 4 black seeds.
J.F.
