The morphostructure of Oxalis incarnata bulbs

Abstract

The morphostructure of the bulbs of Oxalis incarnata in the conditions of dormancy and the plant’s growth and development are described. The plants were grown in two irrigation modes: 1) with regular irrigation during the year, and 2) with limited irrigation in March-October and without irrigation in November-February. The bulbs were analyzed by way of consequent detaching of the scales. Investigated bulbs always had four fleshy scales, while the number of coriaceous and membranous scales varied. Coriaceous scales, together with two fleshy outer scales, make a protective envelope of the bulb.The overground shoot of O. incarnata, just like in other species of the genus, demonstrates monopodial growth and can produce up to five levels of lateral branches. Elongated parts of overground shoots serve for new territories’ useful occupation, while shortened parts produce new particles. Resting buds (bulbils) of three types were observed in O. incarnata: underground axillary buds, overground axillary gemmae, and terminal gemma. Our investigations showed polyvariance both of organogenesis of the resting buds and ontogenesis of plants in general, depending on irrigation regimes. In the case of limited irrigation, the plants of O. incarnata shed the leaves and can produce terminal gemma. While in the case of regular irrigation during the year, they remain evergreen and form gemmae exclusively in the leaves’ axils. We did not observe the formation of terminal gemmae in the case if axillary gemmae were present.The root system of O. incarnata has a complex structure. It consists of two crowns of the filamentary roots, contractile roots, and additional adventitious roots located along the underground part of the shoot during its growth. Such structure of the root system probably ensures better absorption of the water.