The germination behaviour of five Helianthemum species (H. almeriense, H. appeninum,
H. cinereum, H. hirtum, H. squamatum) has been studied under controlled conditions. Constant
15, 20 or 25 1C and alternating 25/15 1C temperature regimes and 16/8 h light/dark photoperiod
conditions were used. Presowing treatments applied were manual scarification, boiling water, hot
water, dry heat and sulphuric acid. Germination values recorded were final germination percentage
and germination rate expressed as days to reach 50% of the final germination percentage (T50).
Incubation temperature had no significant effect on final germination percentage for untreated seeds
of the five Helianthemum species. However, variation due to temperature was significant for scarified
seeds, with the lowest germination percentage attained at 25 1C.