Land plants evolved from a algal ancestor, that if still extant, would be classified as a charophycean alga, with charophyte algae and land plants having two KNOX paralogs, KNOX1 and KNOX2, with specific BELL heterodimerisation partners, providing opportunity for sub- and neofunctionalization of gene activity. In comparison to algae, the diploid generation of land plants underwent two major developmental innovations. First, in contrast to the algal ancestor, the zygote divides mitotically to produce a complex multicellular diploid body. Over a century ago, Bower proposed that the sporophyte generation evolved by a delay in zygotic meiosis, with an insertion of mitotic cell divisions between zygote formation and the production of spores via meiosis. We have shown that a KNOX1 gene in the liverwort Marchantia is expressed in the egg cell is it required to initiate diploid gene expression, confirming a common ancestral mechanism to regulate diploid gene expression and an ancestral function for homeodomain genes in eukaryotes. Second, in charophycean algae the diploid zygote acts as the dispersal (and over-wintering) unit, and is encased in a durable cell wall to protect it during its dormancy. In contrast, in land plants the dispersal entity is the haploid spores, which are coated in sporopollenin — a chemically inert biopolymer considered "the most resistant organic material known" due to its preservation in fossils for hundreds of millions of years. Sporopollenin biochemistry is considered to be a land plant innovation. We investigated the role of KNOX1, KNOX2, their BELL heterodimerisation partners, and downstream targets thereof.