Hawkweeds Hieracium agg are very difficult for the casual botanist to sort out into species. In fact they are an aggregate of hundreds of microspecies which do not hybridise and reproduce without pollination. No ordinary field guide will go into detail about them and so they are generally just identified to genus level. The Field Flora of the British Isles by Clive Stace allows you to key them to 15 groups of related microspecies. If you want to take the identification further you will need the achenes (plumed seeds) and some specialist literature. In addition, Hawkweeds are easily confused with Hawk's-Beards Crepis spp, the difference being that Hawkweed achenes have buff coloured plumes and uneven overlapping bracts under the flowers; Hawk's-beards have white achene plumes and distinct inner and outer rows of bracts. They can also be confused with Nipplewort Lapsana communis, but this species has noticeably fewer 'petals' (no more than 15).
Hawkweeds all have erect stems with at least some leaves up the stems and yellow flowers with strap shaped 'petals' (as they belong to the Daisy family Asteraceae, each 'petal' is actually a floret). The achenes have a ring on top and a plume of brownish 'hairs'.
Below photos of a colony of Hawkweed on the side of a track in the Foret de Preuilly, June.
Private Guide for Groups in the Loire Valley - At Loire Valley Time Travel most of our clients book us for a private tour in our classic 1950s Citroen cars, Celestine and Claudette. Using classic cars ...