Plant Identification Roots, Stems, Leaves and Flowers are the Criteria.
Plant Identification • Many things are taken into consideration when trying to identify a plant. • Roots, stems, leaves and flowers will help in the identification process.
Terminology • In order to be able to identify a plant and put it in the right family, you need to know the terminology to use.
Plant Identification • You have two main categories of plants. • Monocots – grasses, grain crops, lilies, gladiolas, and palm trees
Plant Identification • Dicots - most of the other plants such as the shrubs, trees, and flowers.
Plant Identification • The following sections (roots, stems, leaves and flowers) will show you how to use these for plant identification purposes.
Roots • The type of root will normally help you identify the plant. It will place the plant into a monocot or dicot category.
Types of Roots • Tap Root • Have a main central root and may have some lateral branching • E.g. Carrots
Types of Roots • Penetrate the soil to various depths - some only a few feet, others like the mesquite to as deep as 114 ft.
Types of Roots • Fibrous • Have many roots of equal size and a lot of lateral branching • Fibrous roots are generally much more diffuse and closer to the surface
Types of Roots • This root system can effectively prevent any other plant from becoming established – ex: grasses - idea of a healthy lawn is to compete with weeds
Types of Roots • Adventitious Buds - commonly develop on stems or roots - ex: stolons and rhizomes (Bermuda grass, cherry tree, Sumac and raspberry suckers)
Types of Roots • Prop Roots - augment regular roots for anchorage aid - ex: corn - roots come out above soil and help hold plant up
Types of Roots • Aerial Roots - extend down from the branches into the soil - ex: banyan trees • Pneumatophores- stick up from the mud for the purpose of absorbing oxygen – ex: cypress and mangrove
Types of Roots • Mycorrhizal fungi roots - form associations with soil fungi and act as root hairs increasing the absorption of water and minerals (symbiotic relationship - mutually beneficial) – found on trees in temperate forests such as pines and also on ferns, lettuce, white clover, perennial rye and orchids
Types of Roots • Haustorial - parasitic roots which not only anchor but also penetrate into the hosts vascular system for water and nutrients – ex: mistletoe
Types of Roots • Storage roots - starch and other molecules are stored for growth or flowering needs (ex: carrots, beets and turnips)
Types of Roots • Nitrogen fixing roots - members of the Leguminosae family (alfalfa, peas and clover) have a bacteria that infects their roots and forms nodules. The bacteria are able to fix atmospheric nitrogen, to a form, that the plant can use.
Why Different Types of Roots • All plants are in competition with each other for food and nutrients • By having different types of roots, the plants can reach different depths in the soil and still live side by side with other plants
Roots from Seeds – Monocot vs. Dicot • Tap Root • Seeds contain an undeveloped plant (embryo) • Seed germination - embryonic root (radicle) grows by dividing and elongation of cells
Roots from Seeds • Forms one primary root • Ex: dicots (two leaves emerge from embryo), beans
Roots from Seeds cont. • Fibrous root • Embryos of grasses have a single radicle (root shoot) • Also has other embryonic roots (seminal roots) forming just above the radicle
Roots from Seeds cont. • All of these branch to form the fibrous root • Ex: monocots (one leaf emerges from embryo)
Stems • Flowering plants - divided into two groups, monocots and dicots - stems have major differences in arrangement, distribution of tissues and appearance.
Stems • For identification: type of stem (woody or herbaceous), monocot or dicot, has pubescence (hair) or not (glabrous), shape of stem (square – round), or contains glands.
Monocot stem Dicot stem
Mature Structure of Woody vs Herbaceous Stems • Herbaceous stems • Lack secondary growth - because plants only live one year/growing season (annuals)
Mature Structure of Woody vs Herbaceous Stems • Stems remain soft and flexible. • Buds lack protective scales (don’t need to survive harsh conditions)
Mature Structure of Woody vs Herbaceous Stems • Woody stems • Plants living and growing over multiple seasons have secondary growth (xylem, phloem) increasing diameterof the stems
Specialized Stems • Adventituous stems – can be either rhizomes or stolons.
Specialized Stems • Rhizomes - underground horizontal stems (ex: perennial grasses, bamboo) - may also serve as a storage function (irises) – will grow a plant and roots at a node.
Specialized Stems • Stolons- runners - usually above ground, horizontal stems (really elongated internodes) – will grow a plant and roots at a node - ex: strawberries
Specialized Stems • Tubers - several internodes at the end of an underground rhizome (ex: potatoes) - eyes are axillary buds – where the tuber will grow a plant
Specialized Stems • Bulbs - large bud with small stem at lower end - storage in the form of numerous, fleshy leaves - ex: onion, lily, tulip • Corms - look like bulbs, but are mostly stem tissue with a few, papery leaves on the outside - ex: gladiolus, crocus
Leaves • Leaves are used as part of the identification process along with the roots and stems. • Look of the leaf (margins, venation, and shape), arrangement and whether it is monocot or dicot.
Leaves • Leaves may contain pubescence, glands or thorn like projections. • All of these points are considered when using a leaf for identification.
Parts of a Dicot Leaf • Leaf blade – expanded, usually flat portion of a leaf – contains chloroplasts • Petiole – connects the blade of a leaf to a stem or branch – holds leaf up for better air flow and to catch the light
Parts of a Dicot Leaf • Veins – threads of vascular tissue (xylem & phloem) • Node– place on a stem where leaves or branches normally originate • Stem – used for support of leaf
Where leaf would be attached to the branch or stem at the node. Petiole Veins Leaf Blade Dicot Leaf
Parts of a Monocot Leaf • Node – where leaf arises or originates from • Blade – leaf blade – flat upper portion of leaf • Stem – used for support of leaf, inflorescence, and seed heads
Parts of a Monocot Leaf • Sheath – part of leaf that holds leaf to stem – encases stem • Ligule – membrane-like tissue extending up from the sheath (on inside) – keeps dirt and moisture out – clear membrane on leaf where attaches to stem
Monocot Leaf Blade Sheath Node Collar Auricle Stem Ligule
Parts of a Monocot Leaf • Auricle – small appendages that extend out and sometimes around the stem – found at the junction of the blade and sheath – can be clasping or non clasping appendages
Parts of a Monocot Leaf • Collar – area between the leaf blade and sheath – auricles and ligules are on the inside of this area