Ripe fruits (capsules) containing mature seeds were collected in the field in July 2002 in
several provinces of Spain: H. almeriense in Sorbas (Almerı´a, SE Spain); H. appeninum in
Entrepen˜ as (Guadalajara, central Spain); H. cinereum in Albacete (Albacete, SE Spain); H.
hirtum in Pinilla del Valle (Madrid, central Spain); H. squamatum in Rivas (Madrid,
central Spain). In all trials, four replicates of 25 seeds each were tested for germination on
top of two sheets of filter paper (previously moistened with 3.5 ml distilled water, which
was periodically added) in 7-cm diameter glass Petri dishes. Incubation took place at 16-h
light/8-h dark photoperiod (the light was provided by cool white fluorescent tubes with an
irradiance of 35 mmolm2 s1) under constant temperature regimes (15 1C, 20 1C, 25 1C) or
alternating temperature of 25 1C (light)/15 1C (darkness). Germinating seeds were counted
and removed every 2 days over a 60-day incubation period. The criterion of germination
was emergence of the radical through the seed coat. The time necessary (in days) to reach
50% of the final germination percentage (T50) was calculated by linear interpolation from
the two germination values closest to median germination.