Allozyme Variation and Morphological Relationships of Chenopodium hircinum (s.l.)

Abstract

The domesticated Andean grain chenopod, Chenopodium quinoa, is sympatric with closely related wild types that are classified as two species. Large-fruited (1.5-1.8 mm diam.), broad- leaved plants are placed with C. quinoa, as either subsp. milleanum or var. melanospermum. Plants with smaller fruits (1.0-1.5 mm) and rhombic to tri-lobed leaves are treated as Andean varieties of C. hircinum, a species originally described from the eastern plains of South America. This alignment was evaluated by comparative analysis of electrophoretic and morphometric data taken from pop- ulations occurring throughout the range of C. hircinum (s.l.). Samples from the eastern Andean slopes and plains of Argentina (C. hircinum s. str.) form a coherent group that is positioned at one extreme in the pattern of leaf and fruit variation. These samples, characterized by small, obtuse-margined fruits and acute, lobed leaves, are linked to material from the high Andes through a series of intermediate Andean samples. Andean material shows a wide range of variation in fruit size and shape. Leaf shape is more conservative, although samples from Bolivia trend toward the acute, tri- lobed condition. In contrast to morphological relationships, allozyme variation is simple and well defined. Andean material is homogeneous (I > 0.98), with unique alleles widely dispersed, mainly in southern populations. Populations of C. hircinum (s. str.) are more variable (I = 0.951) and well differentiated from the highland group (I = 0.825) by a relatively common set of unique alleles. Minimal electrophoretic differentiation among Andean samples indicates that the companion weed of C. quinoa is a single biological entity that may represent an Andean element of C. hircinum,