Our first indication of the strong influence of annual precipitation levels on Cynara cardunculus reproductive traits. Numbers of heads per C. cardunculus plant, apparently viable seeds per plant, and seeds produced/m² for the first three years of a five year study, with results of ANOVA in sparsely (<30% cover) and heavily (> 50% cover) invaded sites. n = 12 random individuals per site. Tukey’s post hoc test indicates significantly different means. Rainfall (inches): 1997-98 (29.1), 1998-99 (7.87), 1999-00 (11.02).
Site | 1998 | 1999 | 2000 | p |
Heads per plant | ||||
Heavy | 4.8 ± 0.7ª | 2.9 ± 0.3b | 2.3 ± 0.4b | 0.005 |
Sparse | 3.8 ± 0.4ª | 3.4 ± 0.4ª | 3.6 ± 0.4ª | 0.814 |
Seeds per plant | ||||
Heavy | 798.3 ± 171.8ª | 304.1 ± 82.9b | 176.6 ± 59.3b | 0.001 |
Sparse | 643.4 ± 95.8ª | 179.4 ± 82.1b | 556.7 ± 959.3ª | 0.002 |
Seeds per m² | ||||
Heavy | 1337.21 ± 227.7ª | 439.1 ± 55.3b | 138.3 ± 7.0b | 0.005 |
Sparse | 117.96 ± 18.6ª | 13.4 ± 1.5b | 102.07 ± 22.0ª | 0.004 |