Sweet potato (Ipomaea Batatas)

A member of the Convolvulaceae native to South America and common in Madeira. The cut-leaved sweet potato was introduced to the island in the mid-17th century; the form with entire or angular leaves did not begin to be cultivated until 1845, the first specimens to appear here having come from Demerara.

Madeirans call the aerial part of the sweet potato plant rama (vine), and it is by means of this that the plant is propagated.

Sweet potatoes are one of the staple foods of the Madeiran population, and they can also be made into a very tasty preserve.

On the subject of the sweet potato, which is grown on a large scale in Madeira and eaten in such great quantities by the inhabitants of the rural parishes, we shall transcribe an article published some years ago in Portugal Agrícola. It contains interesting information that may be of use to Madeirans who grow this tuber.

The sweet potato (Batata edulis), a plant of the Convolvulaceae family introduced to Madeira in the mid-17th century, thrives on this island from close to the sea up to the limits of the cultivated zone. In Madeira it is propagated from cuttings, which are planted all year round in the low-lying zone and from May to July at higher elevations.

Some farmers take two or even three harvests of sweet potatoes from their land each year, but this happens only in warm, low-lying places where rainfall is less abundant. On high ground only one crop of these roots is obtained each year, and it is generally harvested before the rainiest season, to prevent the damp from making the tubers watery and hard to keep. The sweet potato is not demanding as to the quality of the soil, but it gives more abundant yields in dry, deep soils of medium consistency.

Two quite distinct varieties of Batata edulis exist in Madeira: the variety cordifolia, with entire or almost entire leaves, and the variety digitata, with leaves more or less deeply lobed. The latter is the older on the island; the variety cordifolia was introduced in 1845, the first specimens grown here having come from Demerara.

Madeirans give no particular names to the tubers of the sweet potato plant, but the rama (the aerial part of the plant) receives various names according to its colour and appearance. In the variety cordifolia the following two sub-varieties are common: rama inglesa and rama de São Martinho, both of which produce white potatoes.

In the variety digitata, much richer in forms than the preceding one, the following sub-varieties may be noted as common: rama Machiqueira or de Sandwich, da Magdalena, frizada, de graveto, braço de rei, brazileira, feiticeira and de Cayenna. The tubers of the first four are white, those of the next two reddish, those of the penultimate somewhat violet and those of the last yellow. The rama da terra, introduced in the 18th century and today very rare on the island, also belongs to this variety.

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The rama da terra usually produces larger, sweeter and floorier potatoes than a great many of the modern sub-varieties; it has, however, the drawback of needing more time to form roots and of giving only one harvest each year, which makes it unprofitable and therefore less valued by Madeiran farmers. Its roots are white, rarely yellow.

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The roots of the sweet potato are starchy, sugary, pleasant to the taste and more easily digested than the tubers of the solanaceous plant known on the island by the name of potato (Madeiran semilha). Madeirans eat them on a large scale, and also give them to their domestic animals, which devour them greedily. From them a preserve much prized by foreigners is made.

The vines of the sweet potato make excellent food for livestock. In Madeira it is customary to give them to animals only when green, but they could also be used as dry fodder, provided care is taken to gather and prepare them before the rains.

The sweet potato, which, as we have said, is propagated on the island only by cuttings, is grown in furrows, usually together with other plants such as cabbages, maize, beans, peas, etc. The sweet potato plants usually occupy one side of the furrows, often spreading over the ridges.