Eggplant Leaf Identification: And How It Differs From the Other Nightshades

What an eggplant leaf looks like

Large, broad and oval, often with a slightly wavy or lobed margin rather than a clean edge. The surface is soft, matte and velvety rather than glossy, and it has a greyish or purplish tinge on the veins and the underside.

The stems are thick and often purple-tinged, and they are covered in fine hairs. Rub a leaf and it smells faintly musty and green rather than the sharp, resinous smell you get from a tomato leaf.

The overall impression is of a soft, dull, slightly dusty leaf on a sturdy purple-tinged stem. If you are looking at something glossy and thin, you are looking at a capsicum.

The nightshade comparison

The features to check, in order

• Is the leaf simple or compound? A single leaf blade is eggplant or capsicum. A leaf divided into separate leaflets is tomato or potato.
• Is the surface glossy or matte? Glossy and thin is capsicum. Soft, matte and velvety is eggplant.
• Are there tiny leaflets between the big ones? That is potato, and it is unmistakable once you see it.
• What does the stem look like? Eggplant and potato stems are hairy. Tomato is hairy and green. Capsicum is smooth.
• What colour are the veins? Purple or greyish-purple veining points strongly to eggplant.
• What does it smell like? Tomato is the one with the strong, unmistakable resinous smell. Eggplant is faint by comparison.

One thing that matters more than the identification

Nightshade leaves are toxic and must never be eaten. Tomato, potato, eggplant and capsicum leaves all contain solanine or related compounds, and they cause illness.

This is worth stating plainly because the question "what is this leaf" sometimes means "can I eat this leaf", and with nightshades the answer is always no. The fruit is the crop. The leaves are not food.

Potato leaves and green potato skin are the most dangerous of the group, and they are the ones people are most likely to encounter without realising.

Common problems on eggplant leaves

• Yellowing between the veins on the older leaves is magnesium deficiency, the same as on cucumbers and tomatoes. Epsom salts and a balanced feed fix it.
• Pale stippling with fine webbing in the leaf joints is spider mite, which eggplants get badly in hot dry weather.
• Large ragged holes are caterpillars, usually at night. Check with a torch.
• Sudden wilting of the whole plant, with no leaf symptoms, is usually verticillium wilt, which lives in the soil and cannot be cured. Remove the plant and do not replant a nightshade there.
• Purple-tinged leaves in cold weather are normal. Eggplants sulk below about fifteen degrees and it shows in the leaves.

I grow tomatoes, capsicums, chillies, eggplants and potatoes, and every year the labels fade or the dog pulls them out. Every year I end up standing in the patch trying to remember which leafy thing is which.

Eggplant is the hardest of the five, because its leaves are the least distinctive. Tomato leaves are obviously divided into leaflets. Potato leaves have those little leaflets between the big ones. Capsicum leaves are glossy and thin. Eggplant is just a big soft oval leaf.

So the useful answer is not "that is an eggplant" but "that is an eggplant, and here is how it differs from the three things it could be instead".