665 measurements of nectar concentration and 983 of nectar volume per day, distributed among 37 out of 43 species of flowering plants examined, are recorded and analysed. Nectar production per unit area per season was substantially less at Lake Hazen, 820 N, than at Churchill, 580 N. Ne'ctar yield in mg sugar/flower/day was higher at Lake Hazen than at Churchill in eight of the ten species for which data were obtained at both localities. There is competition between flowers for pollinators rather than among pollinators for nectar. Heliotropic flowers, notably Dryas and Papaver, focus sunlight falling on them in the region of the germ cells; it is shown that the thermal increments obtainable by black insects resting in these flowers can be important. 184 different plant species - insect species associations are reported, based on about 350 observations and 760 insect specimens; these associations fall into 9 activity categories (some into more than one), as follows: ambush (6), basking (4), flying over (20), hidden in (20), courtship behaviour (1), nectar feeding (23), ovipositing (2), pollen feeding or collecting (12), resting on or uncertain (96). It is concluded that flowers and floral groups are important as aggregation centres for insect populations in this environment.