Rhizomatous plants forming patchy expansions show high potential for sand fixation in mobile dunes with heterogeneous resources, yet resource allocation strategies among different plant parts and reproductive methods during patch expansion remain poorly understood. This study investigated the growth dynamics and allocation of key morphological traits (plant height, leaf area, and rhizome length) of Psammochloa villosa across clonal patches of different sizes in the desert–oasis ecotone of Northwest China. Results revealed that aboveground traits exhibited rapid unimodal growth, peaking in the order of plant height followed by leaf area, whereas rhizomes showed prolonged bimodal growth (approximately 8 months) with delayed peak phases. During clonal expansion from micro to medium patches, asexual clusters decreased the growth rate and increment of leaf area per ramet but markedly increased that of rhizome length, reflecting a shift from photosynthetic to clonal investment. The ratio of belowground to aboveground growth and their allometric relationship both shifted when patch size reached an lg‐transformed area of 2–3, while sexual reproduction occurred exclusively in large patches (lg‐transformed area more than 4). The maximum growth increment of aboveground traits in sexual clusters was more than double that in asexual clusters, indicating a high energy cost associated with sexual reproduction. This was supported by increased aboveground allocation in asexual ramets alongside reduced absolute rhizome growth, despite elevated relative rhizome growth rates. Consequently, sexual reproduction occurs at the expense of rhizome expansion, requiring extensive clonal expansion to accumulate resources in the resource‐limited environment. P. villosa thus adapts to arid sandy habitats through stage‐specific resource reallocation during patch expansion, with long‐term spatial occupation via rhizomes preceding the costly sexual reproduction. These insights elucidate the persistence mechanisms of sand‐fixing rhizomatous herbs and highlight the need to quantify threshold patch sizes and ages to enable sexual reproduction across environmental gradients.

Flowering phenology is a critical life-history trait determining the reproductive success of entomophilous plants in alpine ecosystems. However, comprehensive characterizations and cross-level comparative studies of these phenological patterns remains limited. In this study, we conducted high-frequency phenological monitoring of 36 entomophilous species across 15 families in a typical alpine grassland in the Qilian Mountains, extracting parameters at the individual, population, functional group, and community levels. Our results demonstrate that the community flowering season lasted approximately 100 days, beginning in early June and terminating in early September. Community flower abundance exhibited a bimodal distribution, reaching distinct peaks in early July and early August. Overall flowering synchrony among plants was generally low, indicating clear temporal niche differentiation. The plant community comprised early-, mid-, and late-flowering groups. The temporal overlap of early- and mid-flowering species jointly contributed to the first floral peak in early July, whereas late-flowering species drove the second peak in early August. Among these functional groups, the early-flowering group accounted for the lowest proportion of species, whereas the late-flowering group accounted for the highest. Both early- and late-flowering groups tended toward mass-flowering strategies, while the mid-flowering group leaned toward steady-flowering. At the interspecific level, earlier-flowering species typically exhibited shorter flowering durations and more right-skewed floral distributions, meaning the interval from the first to the peak flowering date was shorter than that from the peak to the last flowering date. At the intraspecific level, individuals that initiated flowering early or late typically exhibited longer flowering durations but lower synchrony with conspecifics; conversely, individuals blooming during the middle of the population’s season exhibited the opposite pattern. These findings systematically delineate the hierarchical temporal structure of alpine entomophilous communities, objectively reflecting the differential utilization of a limited growing season through inter- and intraspecific phenological variation.