Abstract:

The genus Ammopiptanthus (Fabaceae) , a typical evergreen broadleaf shrub of the northwestern deserts of China, comprises two species: A. mongolicus and A. nanus. Both are semi-endemic and relict species in China. In order to detect the differences between the two species in flowering phenology as well as factors influencing flowering, we investigated and compared flowering in the Turpan Eremophytes Botanical Garden in 2004 and 2005. (1) The two species are similar in terms of flowering frequency, flowering order of inflorescences, flowering amplitude curves, and the mean longevity of individual flowers, but differ consid-erably in the onset, the flowering duration of individuals, flower number per inflorescence, mean and fre-quency distribution of duration, and flowering amplitude. (2) At both individual and population levels, onset was earlier and duration was longer in A. mongolicus than in A. nanus . (3) A. mongolicus bore more flowers and had longer duration of flowering than A. nanus. There were significant differences both in flower number (F=17.51, P<0.01) and duration of inflorescences (F=14.08, P<0.01) between the two species. (4) The flow-ering of both species initiated from near the base spreading to the two ends, presenting a unimodal flowering amplitude, but A. nanus had a relatively higher flowering amplitude. (5) There were obvious differences in the frequency distribution of duration of inflorescences between the two species, but the mean longevities of individual flowers were similar (about seven days). (6) Pearson correlation analysis showed that the fruit number of an inflorescence was positively correlated with its flowering number per day(A. mongolicus, r=0.885, P<0.05; A. nanus, r = 0.827, P<0.01), while the flowering and fruit number of inflorescences per day had different correlations with onset, which may result from the different pollinators and genetic charac-ters of the species. The results showed that the similarity in flowering parameters in two species of Am-mopiptanthus may be explained by their phylogenetic relationships, while the differences, which are heredi-tary, may result from their evolutionary history in heterogeneous habitats. The differences in flower number and the duration of inflorescences in two years may be caused by temperature changes. These results can provide useful information for research on reproductive biology and conservation for the two Ammopiptan-thus species.

Key words: molecular phylogenetics, biodiversity conservation, evolutionary significant units, population proce