Abstract:

Rhizomatous grasses are typical clonal plants with a geophytic life form， often found as dominant species widely distributed in China’s northern grasslands. This study synthesizes fragmented research findings on various rhizomatous grasses， identifies common patterns from their shared characteristics， and elucidates the biological， ecological， and evolutionary mechanisms underlying the convergent adaptation of plants with the same life form. Based on three decades of related research， 12 representative rhizomatous grass species with robust datasets were selected. For each species， three land-use types： grazed pasture， mown meadow， and fenced grassland， were analyzed to compare and theoretically interpret the age structure and senescence processes of population modules. Key findings include： 1） All 12 species exhibit finite lifespans in their modules. Tiller nodes can reproduce up to four generations， with a maximum lifespan of five years， while rhizomes have a maximum lifespan of four years. 2） The age structures of three module categories （tillers， rhizomes， and buds） are predominantly expanding type， except in some cases in grazed pastures where stable age structures are observed. 3） Senescence in tiller nodes accelerates significantly from the second age class， whereas rhizome senescence progresses more gradually. The convergent adaptation of rhizomatous grasses has led to a reproductive strategy wherein rhizome buds replenish first-age-class tillers. This strategy achieves two evolutionary milestones： for individuals， once seedlings establish， the genetic lineage of the maternal plant attains longevity or even virtual immortality. For populations， it sustains expanding age structures in modules， expands spatial occupancy， and reduces competition between tillers derived from rhizome buds and those from parental tiller node buds of varying age classes. These adaptations hold critical evolutionary significance for population survival and proliferation.

Key words: life-form, clonal plants, vegetative propagation, modules, age spectrum, tiller productivity, rhizome storage capacity