On the limits of drought—Life history of Gagea bulbifera (Liliaceae)

• We report the life history of Gagea bulbifera.
• Plants show high seed set, but form only ocasionally bulbils.
• G. bulbifera assumes “quasi-annual” life style to adapt on arid conditions.
• Among 53 investigated plants we found 48 genets.
• Dispersal relies on sexual reproduction, a rare phenomenon in the genus.

The life history of the geophyte Gagea bulbifera (Pall). Salisb. was studied by quantitative analyses of plant structures, estimation of resource allocation by measuring the nitrogen content of different plant organs, and employing Amplified Fragment Length Polymorphism (AFLP) analyses for an estimate of genetic diversity. The species occurs in arid steppes and semi deserts in large populations with densities of 50–250(–400) individuals per square meter. Adaptations on this extreme habitat include (i) sclerified roots protecting the dormant bulb against summer desiccation, (ii) extremely high seed set compared to other species of the genus, and (iii) only occasional formation of a single basal bulbil. Less than 9% of adult, flowering plants formed a basal bulbil in the studied populations in southern Kazakhstan. Flowering plants are 5–15 cm tall; develop two basal and 2–5 stem leaves, each with a tiny (<0.5 mm) axillary bulbil; 1–2(–4) flowers and 119 ± 90 seeds. If nitrogen is taken as a proxy for resource allocation, adult plants invest up to 30% of the total nitrogen content in seeds. This amount increases with replacement bulb size and diverts an increasing amount of resources from the latter, explaining the comparatively small size of the plants. Much less (<5%) resources are found in basal and axillary bulbils. Using AFLP we found 48 different genotypes among 53 plants tested, indicating predominant recruitment by seeds. These adaptations, coming close to an annual life style, place G. bulbifera apart from most species of the genus.