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Plant morphology determines the access to soil resources, a feature crucial for early growth in annual species. Plant growth and root traits in little-known species of Andean chenopods were compared with the hypothesis that plants from low-resource habitats show traits that enhance resource capture. Three cultivated Chenopodium populations (two populations of the tetraploid Chenopodium quinoa Willd., one population of the diploid Chenopodium pallidicaule Aellen) and one population of their wild tetraploid relative Chenopodium hircinum Schrad. were grown in pots under nonlimiting conditions over nine weeks of early vegetative growth. All populations followed the same sequence of biomass allocation and showed similar maximal values of shoot and root relative growth rates (RGR). Population differences in plant biomass, net assimilation rate, total root length, and specific root length were associated with seed mass ranking and species ploidy level. Chenopodium quinoa produced less branched stems and maintained high root RGR for a longer time than the other two species, and the C. quinoa population from low-resource habitat showed a faster main root growth. These results show that C. pallidicaule developed a plant growth syndrome adapted to cold, high-altitude habitats, while C. quinoa from low-resource habitats showed an improved capacity to explore soil at depth in early growth stages. Key words: biomass allocation, phenotypic variation, plant growth analysis, root growth, root morphology, wild and cultivated species. La morphologie des plantes determine l'acces aux ressources du sol, un element crucial pour la croissance juvenile des plantes annuelles. La croissance des plantes et les traits racinaires de chenopodes peu connus des Andes ont ete compares avec l'hypothese que les plantes d'habitats pauvres en ressources presentent des traits qui ameliorent la capture des ressources. Trois Chenopodium cultives (deux populations tetraploides de Chenopodium quinoa Willd., une population diploide de Chenopodium pallidicaule Aellen) et une population de leur parent sauvage tetraploide Chenopodium hircinum Schrad. ont ete cultives en pots en conditions non limitantes durant neuf semaines de croissance vegetative. Toutes ces populations montrent la meme sequence d'allocation de la biomasse et des valeurs similaires des taux de croissance relative (RGR) des tiges et des racines. Les differences inter-populations de production de biomasse, taux d'assimilation nette, longueur racinaire totale, et longueur specifique des racines sont associees a la masse des graines et au niveau de ploidie des especes. Chenopodium quinoa produit des tiges moins ramifiees et maintient des RGR de racines plus eleves durant plus longtemps que les deux autres especes, et la population de C. quinoa issue de l'habitat pauvre en ressources presente une croissance plus rapide de la racine principale. Ces resultats montrent que C. pallidicaule developpe un syndrome de croissance adapte aux habitats froids de haute altitude, tandis que C. quinoa de l'habitat pauvre en ressources montre une meilleure capacite d'exploration du sol en profondeur pendant la phase de croissance juvenile. Mots-cles : allocation de biomasse, variation phenotypique, analyse de croissance des plantes, croissance racinaire, morphologie racinaire, especes sauvages et cultivees., Introduction The morphology of individual plants largely controls the balance between resource capture and resource use during the plant's life cycle (Garnier 1991; Reich et al. 1998). Both natural and [...]