Fennel (Foeniculum vulgare) is native to the Mediterranean region and southwestern Asia. It is a highly aromatic erect perennial herb, that has become naturalised in the UK. It is one of three herbs used in the manufacture in Absinthe. The bulb, foliage, and seeds of the fennel plant are widely used in many of the culinary traditions of the world. It has many "medical" uses, from treating flatulence to calming bronchitis and coughs, but it is also the host to many insects. Several species of lepidoptera use it as their food plant, and many more feed on the pollen.
It think it has a very attractive, if understated glaucous green leaves and stems with tiny yellow flowers.
The leaves grow up to 40 cm long; they are finely dissected, with the ultimate segments filiform, about 0.5 mm wide.
The flowers are produced in terminal compound umbels 5–15 cm wide, each umbel section with 20–50 tiny yellow flowers on short pedicels. Here a Ladybird is just landing. I didn't identify this at the time, but it may well be a Harlequin Ladybird, a non-native pest species that is threatening our native species.