Solanum lycopersicum



Solanum lycopersicum

L. 1753

pronounced: so-LAH-num ly-koh-PER-sick-um

a.k.a. Lycopersicon esculentum

Mill. 1768

pronounced: ly-koh-PER-sick-on ess-kew-LEN-tum

(Solanaceae — the nightshade family)


common name: tomato

Solanum is the ancient Roman name for the deadly nightshade; lycopersicum is a mixture of Greek and Latin, λυκος (lykos), a wolf, and persicus, Persian. Some think that the –persicum came via the Prunus persica, the peach, and that the tomato is ‘Wolf peach’, from the belief that it was poisonous, as are so many members of the nightshade family. The Persian connection is because, when the peach was introduced to Europe, it was thought to have originated from Persia; we now believe it was of Chinese origin.

There are two schools of thought about the tomato’s botanical name. Originally put in Solanum by Linnaeus, it was later assigned to Lycopersicon because of the appendaged anthers of its flowers. However, recent DNA sequencing has firmly returned it to Solanum, although not all authorities accept this.

The tomato originated in South America, and was spread around the world after the Spanish colonization of the Americas. Genetic evidence shows that the progenitors of tomatoes were herbaceous green plants with small green fruit in the highlands of Peru. One species, Solanum lycopersicum, was transported to Mexico, where it was grown and eaten by Mesoamerican civilizations. Just when it was domesticated is not known; but the first domesticated fruit may well been a little yellow fruit, similar in size to our cherry tomato. Aztec writings mention that tomatoes were prepared with peppers, corn and salt. The word ‘tomato’ comes from the Aztec tomatl, literally meaning ‘the swelling fruit’.

Tomato plants grow as a series of branching stems, with a terminal bud at the tip that does the actual growing. When that tip eventually stops growing, because of either pruning or flowering, lateral buds take over and grow into other, fully functional vines. The vines are typically pubescent, being covered with fine, short hairs. These hairs facilitate the vining process, turning to roots wherever the plant comes into contact with the ground and moisture. Most tomato plants have compound leaves, and are called ‘regular leaf’ (RL) plants; but some cultivars have simple leaves known as ‘potato leaf’ (PL) style because of their resemblance to that close cousin. The RL leaves are 1 – 25 cm long, odd-pinnate, with 5 – 9 leaflets on petioles, each leaflet up to 8 cm long, with a serrate margin; both the stem and the leaves are densely glandular-hairy.

The flowers, appearing on the apical meristem, have the anthers fused along the edges, forming a column surrounding the pistil’s style. Flowers in domestic cultivars tend to be self-fertilizing. They are 1 – 2 cm across, yellow, with 5 pointed lobes on the corolla; they are borne in cymes of 3 – 12 together.

The tomato fruit is classified as a berry. As a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising the pericarp walls. The fruit contains hollow spaces (locular cavities) full of seeds and moisture. The number of the locular cavities varies among cultivated species according to type, from 2 to many.

The tomato plant is a great favourite with Lepidoptera caterpillars, including those of:

      • the Cotton Cutworm Spodoptera litura;
      • the Tomato Grub Helicoverpa armigera;
      • the Australian Native Budworm Helicoverpa punctigera;
      • the Browntail Gum Moth Euproctis lutea;
      • the Beet Armyworm Spodoptera exigua;
      • the Black Cutworm Agrotis ipsilon;
      • the Australian Cabbage Looper Chrysodeixis subsidens;
      • the Tobacco Looper Chrysodeixis argentifera;
      • the Tomato Looper Chrysodeixis acuta;
      • the Eggfruit Caterpillar Sceliodes cordalis; and
      • the Potato Tuberworm Phthorimaea operculella.

Is the tomato a fruit or a vegetable? You may think that the answer to this age-old question does not matter, but it certainly does in the USA. The 1887 tariff laws imposed a duty on vegetables but not on fruit. The US Supreme Court ruled on May 10th, 1893, that the tomato is a vegetable, based on the popular definition that classifies vegetables by use: they are generally served with the main meal, and not for dessert. It should be noted that the court was not ruling on a botanical issue: botanically speaking, it is certainly a fruit!


Photographs taken in Picnic Bay 2010, 2012
Page last updated 5th April 2019