In flowering plants, you can find seeds in the fruits or in the flowers. 7 What kind of plant does not produce flowers or seeds?ĭo flowering plants have seeds or spores?.6 How are non flowering plants able to reproduce?.5 What is the life cycle of a non-flowering plant?.1 Do flowering plants have seeds or spores?.

These initially contain cells that undergo meiosis to produce microspores. Male gametophytes are produced in t he microsporangia of the male cones. Gametophytes are highly reduced and, especially for the female gametophyte, largely invisible because of its small size and location. The gamet ophyte generation develops from microspores and megaspores produced and retained in the male and female cones. In contrast to the female cones, m ale cones are simple in structure: a branch with tightly packed spore bearing leaves (sporophylls), each with a pair of relatively large sporangia on their lower surface. These expand in the spring/early summer (Figure 2) and dry up and wither a month later. Typically, they are produced in the fall and are visible as a cluster of structures at the base of bud. Male spores are produced in less familiar, but certainly easily observed, male pine cones, which grow more quickly than female cones but are present on the tree for a much shorter time. Male cones wither and dry up soon after release pollen early in the summer but may remain on the plant until fall. Figure 2 Male pine cones are produced in clusters and are located below the current year's growth (expanding needles are seen above the male cones). Upon the upper surface of the scale are the ovules, the structures that develop into seeds. A female cone consists of an axis (stem) bearing scales subtended by bracts, with the scales thought to be derivatives of modified branches. These processes generally take multiple years and the structures one usually recognizes as pine cones have been living and developing over a time of two years or more, with many of the significant events occurring when the cone is much smaller and not as easily observed (Figure1). All these events take place in a location described as an ovule. These are not only the site of megaspore production but also the site of megaspore germination to form a gametophyte, egg production by that gametophyte, egg fertilization and seed development. The cones that most people recognize as 'pine cones' are female pine cones. The sites of spore production are the cones. All conifers, including pines, are heterosporous and produce two kinds of spores, both on the same tree. The plants that are recognized as pines are diploid, sporophyte plants. Pines are the most commonly seen conifers and the group that will be described below but the basic pattern holds for all of the group. Below the cone are clusters of leaves just starting to expand. Female cones appear in the spring at the tip of newly elongated branches. We will consider the details of the life cycle, in particular the form of the female gametophyte and the mechanisms associated with pollination and fertilization, for the five groups of extant seed plants.Ĭonifers Figure 1 Young female pine cone at the stage where it would be pollinated.

Most workers believe that seeds evolved more than once and therefore that there should be no phylogenetic entity corresponding to either seed plantsor to gymnosperms (i.e., seed plants lacking flowers) although these categories do persist. These extinct species are sometimes lumped as 'seed ferns, ' but both the lumping and the designation as a group are not thought to be accurate: they are not closely aligned with ferns and they probably represent a polyphyletic grouping. In additionto these five extant groups, there are several groups of seed plants well represented in fossilsbutno longer present. Ginkgo: a single species that survives only where cultivated.

gnetophytes: a small group of only three genera and around 100 species.cycads: a small group of around 300 species with limited distribution and importance.conifers:, although with only 1000 species, they are very commonly encountered and ecologically and economically important.flowering plants, with 250, 000 species, by far the most diverse and ubiquitous plant group.This chapter fills in some of the details for the five groups of seed plants: The last chapter described, in general terms, what seeds are and what modifications in the general plant life cycle of alternation of generations had to occur in order for seeds to appear. The vast majority of plants that we observe and utilize possess seeds and seed plants dominate most terrestrial habitats. Seeds are a remarkable innovation that have been highly important to the evolution of plant life.

Plants that make spores