A 1999 analysis of pollen grains and plant images on the Shroud of Turin, with its faint image of a crucified man and even fainter images of plants, and alleged by Catholics to be the burial cloth of Jesus, now places its origin in Jerusalem before the eighth century, refuting a 1988 study that placed the cloth as being no earlier than the mid-thirteenth century. The analysis, presented at the International Botanical Congress in 1999, identified a high density of pollen of the tumbleweed Gundelia tournefortii. An image of the Gundelia tournefortii can be seen near the image of the man's shoulder. Some experts have suggested that the plant was used for the "crown of thorns." But the debate about the Shroud of Turin continues as scholars find fault with all the various studies.

    Gundelia tournefortii Linn., called 'akkub or kardi in colloquial Arabic, as well as kankar, is a spiny perennial herb thistle found in Israel, Lebanon, and Palestine. The edible parts are the leaves, stems, roots, and undeveloped flower buds, the last mentioned being the most popular. The plant tastes like a cross between asparagus and artichoke. Even though the plant is sold in Jerusalem markets, especially the young plant's thick stem and undeveloped flower buds, Israelis do not eat it, although the Palestinians do. Several ethnic groups gather these plants in the wild for culinary purposes, including Muslim and Christian Palestinians, Druze, and Sephardic Jews. It is also seen in the markets of Lebanon and Syria.

    Gundelia appears to be native to Syria and Israel/Palestine where it grows abundantly, although some botanists suggest an Irano-Turanian origin. The use of this plant is apparently quite old, being mentioned in the Babylonian Talmud and the Bible. This is the plant called silybum by Dioscorides. Gundelia grows wild and is usually harvested in the morning to be sold in the afternoon at market, an activity done mostly by groups of women from Arab villages. The inflorescent heads are removed before bolting occurs by inserting a knife and clipping the stem base a bit below ground level. Gundelia is best eaten, and traditionally eaten, on the day they are harvested. The fresh heads and the bases of the rosette leaves are trimmed to remove the short, soft thorns before cooking. The most popular preparation for gundelia in the Palestinian Arab villages of northern Israel is one where the heads are cleaned and covered with a chopped meat mixture, they are fried in olive oil and then simmered in a lemony broth.