Gundelia

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Gundelia tournefortii (Asteraceae)

Gundelia tournefortii (Asteraceae): Each spiny bur (involucre) contains one seed-bearing achene. Out of twelve bur-like husks, only three contained potentially viable achenes. The remaining 9 were either blanks or contained aborted seeds. One of the potentially viable achenes was soaked overnight in a giberellic acid solution, and the other two were placed in Arrowhead® spring water. [The GA-3 solution was 500 ppm: 100mg GA-3 powder dissolved in 100ml water, the resulting solution mixed with an equal part of water.] The following morning (October 9, 2003) all three achenes were planted in potting soil. As of 9 February 2004, only the seed soaked in GA has germinated. In its native habitat of Jerusalem and the Near East, the protective burs may act as durable agents of dispersal, possibly carried by flood waters.

Note: Gibberellic acid (GA) is a popular growth hormone used to induce parthenocarpy in which ovaries mature without fertilization. Contrary to some references, 'Thompson Seedless' grapes are not parthenocarpic because fertilization does occur, but the ovules fail to develop into seeds within the maturing fruit. Grape cultivars such as 'Thompson Seedless' are treated with gibberellic acid to order to produce larger fruits with longer internodes. The bunches have wider spacing between the grapes and better air circulation, thus reducing their susceptibility to fungal diseases and rotting within the bunch.

Magnified view of an achene from the spiny bur of Gundelia tournefortii (Asteraceae). The hollow crown at the apex of achene is presumably the pappus.

Gundelia tournefortii: A germinated seedling showing two cotyledons and a new leaf with a spinose margin. This species native to semi-desert areas of Jerusalem and the Near East is related to thistles and artichokes. According to Dr. Avinoam Dannin, Professor of Botany at the Hebrew University of Israel (1988), pollen grains of this species have been identified from the Shroud of Turin. The density of pollen grains is much higher than random samples from the air, suggesting that blooming plants of Gundelia tournefortii were placed on the Shroud during its flowering period of February to May. Some biblical scholars have also suggested that this spiny plant may have been the actual "crown of thorns" worn by Jesus. [Photographed 9 Feb. 2004, planted 9 Oct. 2003.]

Gundelia tournefortii: A germinated seedling showing two cotyledons and a new leaf with a spinose margin. [Photographed 24 Feb. 2004, planted 9 Oct. 2003.]

Note: According to Hind (2013), some scholars think that the tumbleweed referred to in Psalms 83:14 is Gundelia tournefortii.

Gundelia tournefortii: Thistle-like plant photographed near the Zavitan river in the Golan Heights region.

See description of Gundelia tournefortii by Nicholas Hind in Curtis's Botanical Magazine 2013 Vol. 30 (2) pp. 114-138. Published by Royal Botanic Gardens, Kew 2013.