Lemon Basil vs. Basil: A Citrus Hybrid and the Herb It Came From

Lemon basil isn’t just a lemony strain of ordinary basil. It’s a hybrid of hoary basil and sweet basil, recorded by Kew as Ocimum × africanum, with O. × citriodorum, the name on most seed packets, as a synonym.¹ What sets it apart in the kitchen is citral, the lemon-scented compound. In a US field trial it made up 16 to 19% of the oil of two lemon basils, and it didn’t show up among the main compounds of sweet basil grown right alongside them.² So the question at the stove is simple: does the dish want lemon?

Side by side

For each herb in depth, see the lemon basil and basil profiles.

What lemon basil is

Kew gives the hybrid formula as O. americanum × O. basilicum.¹ PROSEA, the Southeast Asian plant handbook, notes that crosses between hoary basil and sweet basil are easy to make but have badly reduced pollen fertility. The naming is messy. PROSEA lists O. africanum as a synonym of hoary basil itself, the plant it calls maenglak in Thai and kemangi in Indonesian.³ The Herb Society of America lists “lemon basil” among the common names of O. americanum, but files named lemon cultivars like ‘Lemon’ and ‘Sweet Dani’ under O. × citriodorum.⁴ So “lemon basil” in a Thai or Indonesian market and ‘Mrs. Burns’ Lemon’ from a Western seed catalog may not be exactly the same plant. Our lemon basil profile lays out the naming in full.

Sweet basil is the species O. basilicum, the everyday culinary basil. Genovese is one cultivar of it (see Genovese basil vs. sweet basil).

The difference in the oil

The Purdue University cultivar trial grew lemon and sweet basils in the same field and distilled them the same way, so these rows compare like with like:²

Both kinds share linalool. Citral is what sets them apart, and the Purdue authors concluded it was the predominant compound in all the lemon-scented basils.² A 2018 Chiang Mai University study of a lemon basil grown in northern Thailand found estragole at the top of its oil, with citral and neral behind it, and anise and citrus scents dominant.⁵ That study reported concentrations in µg/mL, so you can’t line it up against the Purdue percentages. It does show that some lemon basils also carry estragole, a principal compound of sweet basil oil.⁶ PROSEA notes that hoary basil varies too, with citral, camphor and methyl cinnamate in varying proportions.³

You’ll often read that limonene drives lemon basil’s scent. Neither study lists limonene among the main compounds.²⁵

Differences that change the dish

Where lemon belongs. Lemon basil suits dishes that welcome citrus: fish and seafood, chicken, salads, fruit. PROSEA says hoary basil’s fragrant leaves get added to dishes with a fishy or unpleasant smell, and that its young leaves are eaten raw as a side vegetable in Indonesia, Malaysia and Thailand.³ In Laos, a soured bamboo soup published by the UN’s International Fund for Agricultural Development calls for a handful of lemon basil leaves (or holy basil), added after the fish sauce near the end.⁷ Where lemon would be out of place, like a classic marinara or a Genoese pesto, stick with sweet basil.

Drinks and desserts. The Herb Society of America calls lemon and cinnamon basils unexpected but flavorful additions to desserts, uses lemon basil in muffins, basil syrups and a fruit cooler, and recommends ‘Mrs. Burns’ Lemon’ for vinaigrettes, drinks and desserts. Its basil syrup recipe allows anise, cinnamon, green or lemon basil,⁴ and only the lemon one brings citrus. A lemon basil syrup also makes a nice base for lemonade.

Heat. LSU AgCenter puts basil among the delicate herbs best added a minute or two before cooking ends, because long heat costs flavor and aroma,⁸ and the Herb Society says to add basil in the last few minutes.⁴ That goes for both. We couldn’t find a source comparing how well citral and linalool survive cooking in the leaf.

Dried. Lemon basil is rarely sold dried. The Herb Society says most experts see no comparison between fresh and dried basil in flavor,⁴ so dried basil is a poor stand-in for fresh lemon basil.

Can one stand in for the other?

We don’t have a lemon basil substitutes page, so treat both swaps below as starting points.

• Sweet basil for lemon basil. Use the same amount of fresh basil and add finely grated lemon zest. Start with about 1/2 teaspoon of zest per cup of loosely packed leaves, and taste. Basil alone gives you the basil but not the lemon. Skip dried basil here.
• Lemon basil for sweet basil. Use the same amount where a lemon note will help, like salads, fish, chicken or a summer pesto built with that in mind. In tomato sauces and classic pesto, you’ll notice the lemon.

Safety

Some lemon basils, like the Thai sample above, contain estragole.⁵ The EU Scientific Committee on Food concluded in 2001 that estragole is genotoxic and carcinogenic, based mainly on studies in mice, and couldn’t set a safe exposure limit.⁹ It didn’t single out lemon basil or tell people to stop eating basil. Our basil profile covers that evidence. We couldn’t find a nutrient analysis of lemon basil itself, so don’t carry sweet basil’s figures over to it.

What isn’t known

• The like-for-like comparison is one 1999 field trial with one seed lot per cultivar.²
• No source we opened compares the leaf width or color of lemon basil and sweet basil.
• Lemon basil’s place in Indonesian curries and in the Malaysian rice salad nasi ulam comes up a lot. We couldn’t find a source that names it as an ingredient in either.

Related

• Lemon basil and basil profiles
• Genovese basil vs. sweet basil, holy basil vs. basil, basil vs. Thai basil
• Lemon balm, lemon verbena, lemongrass
• How to store basil, too much basil