All kinds of plants belong to the kingdom Plantae. They are divided into two groups depending on whether they are seed-bearing plants or plants without seeds. Plants are also classified by their genera, families, and species. This type of plant classification allows for easy identification of plants and makes them easier to study.
Plants classifications also depend on their vascular system. Non-vascular plants such as algae are primitive plants or in a lower class of plants and have simple tissue systems to transport water internally. Vascular plants such as shrubs, trees, herbs, and flowering plants have complex vascular tissue to transport fluid and nutrients internally.
The Main Kinds of Plants
All types of plants are classified into two main groups: plants without seeds and plants with seeds.
Plants without seeds are algae, mosses, ferns, and liverworts. These unique plant types produce spores that are distributed by the wind. For example, if you look at the underneath of fern leaves, you will notice sporangia which are tiny structures containing spores.
Plants with seeds are all kinds of flowering plants, cycads (palm-like plants with cones), conifers (such as spruce, firs, pines, junipers and cedars), and Ginko.
Flowering plants produce seeds that are protected within their fruit. These fruits can be soft fruits such as apples, oranges, or berries, or they can be hard like all types of nuts.
Plants with cones, mostly evergreen trees, are another kind of vascular plant with seeds.
Different Kinds of Plants Without Seeds (Pteridophytes, Bryophytes)
Let’s look at the 4 main groups of plants that reproduce without seeds:
Algae
Kelp is a type of plant without seeds
Kelp is a type of large brown algae and it’s also an edible seedless plant
Algae can be tiny microscopic organisms called phytoplankton that is a food source of many marine animals. Or, some types of algae are commonly called seaweed and are found in waters around coastlines.
There is also some confusion about whether species of algae are truly types of plants. Like many plants, algae use a process of photosynthesis to make food. Interestingly, some types of algae seem to have the ability to “eat” other organisms similar to animals. However, most people view algae as a type of plant.
Green algae
Green algae generally grow in freshwater, although they also grow in saltwater. Individual alga (singular of algae) of some species are tiny microscopic organisms. If they are in abundance, they can turn ponds or seawater green. Similar to brown algae, some green algae grow as seaweed.
Red algae
Red algae (Rhodophyta) consist of the largest group (phyla) of all algae species and the majority grow in marine environments. As with all kinds of algae, red algae are plants that don’t produce seeds. Red algae are also an important food source and are the type that is used for nori. (3)
Liverworts
Liverworts (nonvascular flowerless plants)
Liverworts include many species of plants such as Lunularia cruciata (in the picture)
Liverworts are a type of nonvascular flowerless plant that don’t bear seed and are in the division Marchantiophyta. These small leafy plants may be as tiny as 2 mm or grow to 20 mm wide. Liverwort plants tend to flourish in damp places.
Tiny species of liverworts can be difficult to distinguish from mosses. One way to identify liverwort plants is that they are generally smaller and have tiny hair-like structures (rhizoids) they use to absorb water.
Moss
Moss – a type of seedless plant
Moss is a type of small flowerless plant that prefers damp or shady places.
Although mosses were classified with hornworts and liverworts in the Marchantiophyta group, they are now in a classification of their own. There are 8 classes of mosses with the peat-moss Sphagnum being the most commercially important. Sphagnum moss is an unusual plant that is commonly used as mulch, for home decoration, or in the florist trade.
Ferns
Ferns are green plants that thrive in damp shady areas
Ferns are a type of plant that thrives in damp shady areas
Ferns are identified by their green leafy foliage consisting of fronds and pinnae. Outdoors, ferns grow in forests and love damp shady areas. Some of the tallest ferns in the world can grow up to 82 ft. (25 m) tall.
Ferns are also examples of common indoor bedroom houseplants that thrive well in room temperature. Their bushy green foliage and long, trailing leaves can add beautiful greenery to a room. Some common species of ferns to grow indoors include Boston ferns, staghorn ferns, and the bird’s nest fern. Many types of perennial ferns are also popular plants for gardens as they grow in areas where other plants can’t. Ferns are good examples of ground cover plants, especially in shady areas.
Kinds of Plants with Seeds (Gymnosperms, Angiosperms)
Plants with seeds are one of the largest groups of land plants in the world. Seeds from these plants are either encased in a cone or in fruits that protect the seeds.
Cycades
Cycads are seed plants with pinnate leaves and cone-like reproductive structures (strobilus)
Cycads are an exotic group of plants that grow in tropical and subtropical parts of the world. Similar in appearance to palm trees, cycads have woody trunks that sprout large evergreen leaves. Unlike other types of trees, cycads don’t have branches but their leaves grow directly from the trunks.
Seeds from cycad plants are enclosed in cone-like structures. This flowerless tree reproduces by beetles that pollinate the seeds. Scientists say that this ancient exotic-looking plant has changed little since Jurassic times.
