By moving to land, plants had to develop a waxy surface cuticle to reduce unnecessary water loss. These cuticles (tiny openings on plant surfaces) were known as a Stomata, which were mostly found on leaves. These cuticles balanced the needs of a plants for reducing water loss and maintaining CO2 (Carbon dioxide) intake.
By being in an open environment rather than the dense water, plants had to develop a support against gravity, which meant that cell walls and stems had to be strengthened. Many deposit lignin, the main component of wood, were permitted to increase size and branching.
By moving to land, nutrients and water had to be extracted from the soil rather than from the surrounding aquatic medium, and so plants had to develop roots. These roots extracted nutrients and water from the soil, and transported it via vessels up to the rest of the plant (see How Plants Work?).
With increasing adaptation to drier terrestrial habitats the reproduction process of plants had to change as well. As a result the Haploid Phase (the gametophyte) of the plant life cycle diminished and the Diploid Phase (the sprorophyte) became dominant.
The Haploid Phase required a moist environment such as water for free-swimming sperm to reach the female's egg for reproduction. However the adaptation to dry environments led to the elimination of aquatic gametes (swimming sperms).
The gametophyte phase still dominates in the most primitive of plants, like the mosses and their allies.
The Diploid Phase was more suited to land plants due to the dry terrestrial habitats. These plants developed structures, such as spores and seeds, that helped protect reproductive cells from drying out.
The spore contained a Haploid Reproductive Cell surrounded by a hard outer wall. Spores allowed for the widespread dispersal of plant species.
Eventually, most plants developed seeds (a seed is an embryo surrounded by a protective coat). Some seeds also contained Endosperms (a tissue that provided nourishment for the developing embryo). Seeds are more effective at dispersal than spores are.
The sporophyte phase dominates the life cycles of higher plants such as gymnosperms and flowering plants.