Carthamus tinctorius Seeds | Safflower
LATIN NAME: Carthamus tinctorius
COMMON NAME: Safflower
Plant Profile
Safflower is an upright annual with glossy leaves whose margins are tipped with small spines, and its heads carry only tubular florets, orange to red, without the ray florets that give most daisies their petals. The seed is a smooth, four-sided achene with a hard coat, held in a head that ripens unevenly from the outside inwards, which is why harvesting takes judgement.
Science & Biotechnology
The thistle tribe has a doubled past. Comparative genomic work has shown that the lineage containing safflower passed through a whole-genome duplication, which helps explain why safflower has a comparatively large chromosome complement and why some gene families are present in duplicate. The crop has been sequenced, and much of the breeding work since has used that resource to follow the genes behind oil quality and flower colour.
Because carthamin is valuable and the plant is a field crop, tissue culture has been tried as a route to the pigment. Callus and cell suspensions derived from florets and leaves can accumulate the red, and researchers have followed the enzymes that convert the colourless precursor to carthamin. Hairy root and shoot cultures have also been used to study the pathway without committing a field to it.
Uses & Benefits
Silk dyed with safflower has outlasted the garments it was sewn into. The pigment is carthamin, a red chalcone-quinone that forms in the florets and is unlike any other plant red; it is insoluble in water, which is why the traditional process begins by washing the petals to strip the water-soluble yellow away before the red can be coaxed out with alkali and then precipitated with acid. Fabrics coloured that way were found in Egyptian burials, and carthamin remained a luxury dyestuff in Japan and India for centuries.
The English name is a misunderstanding, not a resemblance. Safflower petals were sold as a cheap stand-in for true saffron, and the plant is called false saffron to this day even though the two come from different families and smell nothing alike. The confusion was common enough that early modern dyers had to distinguish the two by weight and by the yellow that runs out of safflower in cold water.
The plant’s antiquity is documented in the driest possible way: safflower garlands and loose florets were recovered from Egyptian royal burials, and the dye itself appears in textiles from the Nile valley and later from the Roman world. Indian and Japanese dyers developed separate schools around it, and the petals were the base of a cosmetic rouge that stayed in use into the twentieth century.
Safflower seed oil is naturally very high in linoleic acid, the polyunsaturated fat that made it a salad and margarine oil for much of the twentieth century. Breeders at the University of California, led for many years by P. F. Knowles, developed the high-oleic types whose oil behaves more like olive oil in a pan, and both classes are grown today, one for the kitchen and one increasingly as a feedstock for industrial and aviation fuels.
The water-soluble yellow fraction is a permitted food colour and turns up in confectionery, pickles and soft drinks, while floret tea, brewed from a pinch of dried petals in hot water, is drunk as a warm infusion in Iran and China and is used as a colouring in rice dishes. Cosmetically the red was the classic cheek rouge, and the pigment still appears in lipsticks sold by carthamin content rather than by shade.
In a hot, well-drained border safflower earns its space as a cut flower and a bee plant, with heads that open over a long stretch of summer. The spines bother some gardeners, so site it at the back of the bed or grow a spineless selection; either way the seed heads that follow feed finches through the late season.
Growing from Seed
Choose the hottest, best-drained ground on the plot and sow direct, because safflower wants full sun and resents wet feet. Place the achenes two to three centimetres deep, in rows forty to fifty centimetres apart, and water once to settle them; after that the plant’s deep roots do the work and irrigation should be sparing.
Do not plan to transplant. Safflower grows a long taproot quickly and a disturbed seedling stalls for the rest of the season, so thin the row in place to about fifteen centimetres, keeping the strongest plants. Where the season is short, sow on a raised ridge that warms early rather than starting under cover.
Wet ground brings stem rot and a wilt that blackens the base of the plant, and dense humid foliage invites rust on the undersides of the leaves. Aphids colonise the young tips in spring and can be washed off with a jet of water. Rotate the crop, keep the rows open to the wind, and clear the stubble after harvest.
Our Take
I grow a short row every year for the colour as much as the seed, and I dry the petals in the shade so the red survives. If you want the dye, look at safflower seed Carthamus tinctorius as the field form, and read my notes on the dried flowers of safflower before you buy anything labelled saffron. For companions in a hot bed, cornflower and milk thistle want the same dry, sunny ground.
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