The tower of jewels

by Patrícia dos Santos

Echium wildpretii H.Pearson ex Hook.f. is probably the tallest of the (flowering) Echium’s described so far. The plant itself grows as a shy stemless rosette, and only before blooming it grows a huge inforescence that can be over 3m tall! E. wildpretii is endemic to the volcanic alpine landscapes of the Canary Islands, its natural distribution ranges from 1300 to 2000 m in altitude. The harsh dry and sunny volcanic peaks where the species is native to has a great temperature variation, going down to -7ºC in the winter and up to over 40ºC in the summer.

The species is monocarpic, which means it dies after flowering. For this reason, the plant uses all the energy it has been producing during all its life to make the biggest inflorescence the possible, with as many flowers as possible. This will surely increase its reproductive success – the biggest the floral display, the more pollinators it will attract. The result is a massive spike with plenty of tiny scorpioid cymes along the spike, a typical character of the family (Boraginaceae), ending up with a ridiculous number of reproductive units. This is why the species is commonly known as “tower of jewels”, the consequence is a great concentration of pollinators and nectar robbers around these inflorescences trying to feed up on the high nectar concentrations of these little jewels.

The flower colour change among the subspecies this taxon encloses: E. wildpretii ssp. trichosiphon (Svent.) Bramwell is native to alpine zones of the island of La Palma and bears pink flowers, in contrast with the Tenerife endemic, E. wildpretii ssp. wildpretii that has red flowers.

Olesen JM. 1988. Floral biology of the Canarian Echium wildpretii: bird—flower or a water resource to desert bees? Acta Botanica Neerlandica 37(4): 509-513. doi: 10.1111/j.1438-8677.1988.tb02157.x

Rodríguez-Gironés MA, Santamaría L. 2004. Why are so many bird flowers red? PLoS Biol 2(10): e350. doi: 10.1371/journal.pbio.0020350