Collecting nettle seeds, no easy task!

Collecting Pilea cellulosa fruit on the border with Haiti whilst trying to avoid 300 escaped prisoners. Collecting the fruiting bodies is relatively straight forward but recognising and extracting mature fruit is not.

For a week now I have been accompanying a team from the Jardín Botánico Nacional and Kew’s Millennium Seed Bank on a field trip to collect seed of plants endemic to Hispaniola for banking at the Jardín Botánico and Kew. I have been taking advantage of this trip to collect nettles but also to learn how to harvest and bank their seeds. The Greater Antilles which includes the Dominica Republic  / Hispaniola is a centre for species diversity for nettles and most of the 100 or so species found here are found nowhere else. Given obvious pressure on the island’s forests both in the Dominican Republic as well as in Haiti, banking their seeds could support their reintroduction as a last ditch attempt to prevent their extinction.

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Fruiting Pilea microphylla. For scale the leaves are 3 mm in length. Ripe fuits are brown in colour, immature flowers and fruit pale cream to pale-green.

The seed bank at Kew which banks the seeds of >50,000 species currently has only 14 sp of nettle which for me seemed a little on the low side given that there are about 2,000 species Worldwide. Support from the Bentham Moxon Trust is helping me to increase this figure significantly, both by enabling me to help develop seed-collecting protocols for nettles and so encourage seed banks to collect them, but also because I am learning from them how to collect seeds, something that I can do myself on future fieldwork in collaboration with other seed banks.

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Fruit cluster of what is probably Pilea alpina fruits. The whole cluster is maybe 5 mm across and the ripe fruits are brown. Each seed will probably need to be removed by hand with tweezers!

It might seem odd that collecting nettle seeds would be a challenge, except when you think that a typical fruit is 0.5-1.0 mm in size, barely visible to the naked eye, and that most fruiting clusters consist of a few mature fruit and many immature ones. This means that trying to collect 1,000-3,000 seeds, a typical accession, could involve many hours under the microscope with very fine tweezers and hundreds of fruit clusters! Our team consisted of Wilkin Encarnacíon, Teodoro Clase and Wiluien from the Botanic Gardens, Tiziana Ullian and Efisio Mattana from the Millennium Seed Bank and myself.



One thought on “Collecting nettle seeds, no easy task!”

  1. Amazing to really go out and grasp the nettle. I’m in a place in Spain where there are no nettles. Not sure whether that’s good or bad.
    Have just become interested in botany and spent some time at Kew and Wakehurst Place this year.

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