Euphrasia is a large genus, containing approximately 350 species of hemiparasitic root parasites with a widely disjunct bipolar distribution.
Within the genus, 15 sections have been recognised - section Atlanticae Pugsley contains only 2 species, both endemic to the Azores.
Phylogenetic studies (Gussarova et al, 2008) have shown this section to be rather distinct - it is apparently closer to nearctic annual taxa than perennial plants from the mountains of Oceania and Australasia.
Euphrasia grandiflora is a short-lived perennial herb about 40cm tall.
It is erect or ascending, and usually has multiple branches.
Floral leaves (bracts) are similar but smaller with less hairy margin and up to 12 pairs of obtuse to sub-acute teeth. Leaves and bracts blacken when dried.
The 2 native endemic species are the only examples of the genus Euphrasia in the Azores.
They are easily distinguished from Eurasian/North African examples of the genus (sections Euphrasia and Angustifolia) by their:
E. grandiflora differs from the Western Azorean endemic E. azorica in its:
Isolation and inbreeding may have led to subtle morphological differences between plants on the different islands:
Research on the evolution of Euphrasia has shown that the Azorean species are very distinctive and suggests that they have been isolated from other species for a long time.
Both Azorean species are perennial with large flowers and these characters readily distinguish them from similar species found in continental Europe.
The chromosome number and ploidy level of E. grandiflora (and E. azorica) are currently unknown. The European members of the genus are diploid (2n=22), tetraploid (2n=44) with triploid hybrids between them.
Sepals of a flower.
Forming a headlike mass or dense cluster.
Petals of a flower.
Having a short abrupt point.
Triangular leaf shape
A parasite with chlorophyll - it is not wholly dependant on its host for nutrition.
Group or cluster of flowers arranged on a stem.