Chapter 10: Strategies of Inheritance

Capon revisits Gregor Mendel’s experiments with peas, which revealed the principles of dominance, segregation, and independent assortment, laying the foundation for genetics and supporting Darwin’s theory of natural selection. He contrasts mitosis, where diploid cells divide to produce identical copies for growth, with meiosis, where chromosome numbers are halved to produce haploid spores and gametes, fueling genetic diversity. The chapter then traces alternation of generations across mosses, ferns, gymnosperms, and angiosperms, showing how reproductive strategies evolved from visible gametophytes in mosses and ferns to reduced, dependent gametophytes in flowering plants and conifers. Detailed explanations follow of chromosome segregation and gene sorting during meiosis, illustrating how random assortment creates vast genetic variety. Capon uses plant height in peas (tall vs. dwarf) to explain dominant and recessive alleles, genotypes vs. phenotypes, homozygous vs. heterozygous states, and why recessive traits can reappear after generations of hiding in hybrids. He stresses the unpredictability of crossbreeding, where hybrids often fail to breed true, making vegetative propagation the only way to preserve specific genotypes. The chapter also explores chromosomal abnormalities: aneuploidy (missing or extra chromosomes), which may enlarge organs but is often lethal if essential genes are absent, and polyploidy, where plants contain three or more full chromosome sets. Polyploid plants, such as triploids and tetraploids, are common in agriculture, often displaying sterility, larger size, increased vigor, or improved adaptability. Capon explains allopolyploidy, where chromosome doubling in interspecific hybrids restores fertility, producing cultivars like wheat, tobacco, strawberries, and dahlias. Finally, the chapter turns to modern biotechnology, showing how genetic engineering surpasses the randomness of breeding by directly transferring genes between species, even across kingdoms. By inserting traits for disease resistance, drought tolerance, nitrogen fixation, or pharmaceutical production, scientists can now design “custom-made plants” with qualities impossible through traditional methods. Capon concludes that the future of botany lies in the marriage of evolutionary strategies with biotechnology, reshaping agriculture, horticulture, and even ornamental aesthetics such as the dream of blue roses or red delphiniums.