Arctium

Arctium

Arctium - UK and Ireland : Improving my ID skills and to see if we can get ISpot users a little more familiar with the key diff

Improving my ID skills and to see if we can get ISpot users a little more familiar with the key differences between individual species. Key adapted so more useful for photo ID.
Size ranges (horizontally across the capitulum - easiest to use calipers or mark up a piece of card with size ranges and carry it with you) in mm. Always measure peduncles of the flowers in the terminal group of inflorescences:
1 CORYMBOSE OR SUBCORYMBOSE inflorescence branches (to 2)
2 Plant with petioles of lower leaves solid, capitulum glabrous to sparsely hairy in distal portion:
lappa 24-47 - capitula in terminal clusters stalked (peduncle above 8mm) - corymbose inflorescence branches
2 Plant with petioles of lower leaves (usually) hollow, capitulum usually hairy to woolly (to 3)
3 minus ssp pubens 20-32 - usually grey-woolly or hairy, hooked inner bracts, capitula in terminal clusters stalked (peduncle above ;8mm) (much more hairy than ssp. minus as illustrated)
3 tomentosum - bright white-woolly flowerheads, unhooked inner bracts, and contrasting bright-red purple corolla (rare alien)
(lappa x tomentosum occurs as a rare hybrid)
1 RACEMOSE inflorescence branches, Plant with petioles of lower leaves hollow, capitula glabrous to slightly hairy (to 4)
4 minus ssp minus 15-25 - capitula in terminal clusters more or less sessile (peduncle less than 8mm)
4 nemorosum 27-40 - capitula in terminal clusters more or less sessile (peduncle less than 8mm), woolly when young, becoming glabrous
(lappa x minus will also key out here - usually with both parents and obviously intermediate
29 Jul 2018
JoP