Pomegranate Botany

Pomegranates

The Punicaceae family has only two members one of which is Punica granatum, the pomegranate of commerce. The Punicaceae family belongs to the Order Myrtales which includes Corymbia torelliana, a plant being used as a windbreak around citrus in Florida, Eucalyptus, Melaleuca, Jaboticaba, and guava.             

The pomegranate is a naturally bushy, multi-stemmed plant that tends to maintain its bushiness because of suckers routinely arising from the base. Plants grow to heights of ca. 10-12 feet and commercially are often trained to a single trunk or sometimes three stems (Fig. 1). The plant is normally deciduous. New spring shoots tend to be thin and weepy with thorns. The leaves are shiny and dark green. The plant is essentially monoecious with two types of showy flowers produced on new growth each spring. Flowering may occur over several months with some flowers still being produced into late summer/early fall, but the major bloom period is the spring.

A flower is either male or hermaphroditic. The latter flower type is bell-shaped and self-fertile. Hermaphroditic flowers produce fruit. Male flowers are more trumpet-shaped and do not set fruit. Flower color for many cultivars is orange-red to brilliant red and there are some, especially ornamental types, with “double” flowers (i.e., with extra petals) or some that are pink, white, or some combination of those colors and red. Pollination primarily by insects (bees) leads to fruit set and the development of the inferior ovary.

The mature pomegranate fruit is large, usually 3 inches in diameter, and sometimes as large as 4 to 5 inches. Fruit generally mature in 5 to 8 months and often change from round to a slightly squared-out shape. The fruit of different cultivars are quite diverse in their color, taste, and certain other traits. Peel color ranges from a light yellow to “black” or very dark red/purple. The fruit is distinctive because it retains the calyx (petals + sepals) at one end of the fruit giving the fruit the appearance at maturity of having a small crown attached to it. Internally, the fruit consists of a series of chambers (locules) separated by a membranous septum. Inside each chamber are the seeds which each have a fleshy outgrowth (aril) that contains the edible juice. The seeds range in hardness from very hard (not edible) to soft (easily consumed). The color of the arils also ranges from a light, virtually white, color to very dark red or purple. The flavor of the juice can be inedibly tart to bland to sweet or sweet/tart depending on acidity. Typical soluble solids values for fruit grown in California are 15 to 18%.
The terms “seed” and “aril” are often used interchangeably as if they defined the same thing which is not true. Technically speaking, the “seed” has two parts: the crunchy interior structure that is the part that contains the embryo and is sometimes eaten if it is not perceived to be too hard, and the juicy part or the aril. The aril is a fleshy outgrowth of the seed coat and provides the color of the juice.