Integumentary studies in the Polycarpicae. IV. Liriodendron tulipifera L.

Despite the great differences in type of seed dispersal and seed structure, Liriodendron and Magnolia show similarity in their ovule ontogeny and in the early phases of seed development. The ovule primordium is 3-zonate; the inner integument is dermal, and the outer integument subdermal in origin. The cells of the inner epidermis of the outer integument may undergo periclinal divisions and differentiate into a sclerotic layer. However, the outer epidermis and the subdermal tissue of the outer integument in Liriodendron are not multiplicative and do not differentiate into a fleshy, coloured sarcotesta as in Magnolia, but undergo sclerification. This study is in agreement with Dandy’s (1964) subdivision of the family and supports the generally held view that Liriodendron is the most advanced member of the Magnoliaceae. It is posed that the 3-zonate ovule primordium is basic in angiosperms. This clashes with the classical carpel concept, in which the carpel is interpreted as a metamorphosed leaf bearing ovules on its margins or on the adaxial surface of its lamina.