Histopathology of Seed-Borne Infections - Applied Research Center ...

18 Histopathology of Seed-Borne InfectionsdctovoiiivsnuesvsowvctAFoiiinuBCDEFIGURE 2.6 Vascular supply of ovule. A, Ls of portion of carpel of pea showing vascularsupply of developing ovules from the ventral carpellary trace. B, C, Ls and Ts ovule showingraphae vascular bundle terminating at chalaza. D, E, Ls and Ts ovule to show postchalazaldevelopment of vascular supply. F, G, Ls and Ts ovule of Ricinus showing pachychalaza andpachychalazal bundle. (Abbreviations: dct, dorsal carpellary trace; es, embryo sac; ii, innerintegument; nu, nucellus; oi, outer integument; ov, ovule; ow, ovary wall; vct, ventral carpellarytrace; vs, vascular supply.) (A, Adapted and redrawn from Hayward, H.E. 1938. TheStructure of Economic Plants. Macmillan, New York; F and G, From Singh, R.P. 1954.Phytomorphology 4: 118–121.)scar left on the seed after it has separated from the funicle is the hilum. The funicle,raphe (when present), chalaza, and nucellus form a continuous tissue — the centralaxis of the ovule — and sharp demarcation lines cannot be drawn between them(Figure 2.7A). Generally five types of ovules based on the turning of ovule on stalkand funicle and curvature in its body are recognized. These are atropous(orthotropous), hemitropous (hemianatropous), anatropous, campylotropous, andamphitropous. The anatropous ovule is common in the angiosperms. Bocquet (1959)regards orthotropous and anatropous ovules as basic types, each forming a series ofderived campylotropous and amphitropous conditions. The ontogeny and the formof vascular supply in fully developed ovule, straight or curved, permit the identificationof ovules in the two series, i.e., ortho-campylotropous and ortho-amphitropous,and ana-campylotropous and ana-amphitropous types. If the body of the ovule takesa complete turn on its stalk and funicle so that the micropyle faces upward and theG