Flowering Plants, Part 1

fleurishliving

Jun 21, 20204 min read

Updated: Apr 21, 2021

"Before flowering plants appeared the world was like a Japanese garden: peaceful, somber, green; inhabited by fish, turtles, and dragonflies. After flowering plants, the world became like an English garden, full of bright color and variety, visited by butterflies and honeybees. Flowers of all shapes and colors bloomed among the greenery."

Dale Russell, paleontologist

Botany is the branch of Biology that deals with the study of plants. The word “botany” comes from the Greek word “botane”, referring to plants, grasses, and pastures. Theophrastus (Greek, c. 371 – c. 287 BC), a philosopher, scholar, and a favorite student of Aristotle, is known as the “Father of Botany”. Theophrastus wrote 227 major works as well as a number of shorter ones and was the first headmaster of the Botanical Garden which was founded by Aristotle. He was the first to use botanical definitions and nomenclature and the first to describe that leaves were used in the nutrition of the plant. He was involved with the study of plants that were brought to Greece from Asia by Alexander the Great during his expeditions.

Botanists call flowering plants Angiosperms (Magnoliophyta) from the Greek words for "vessel" and "seed." Angiosperms make up more than 90% of plant life and are the most diverse group of land plants with 64 orders, 450 families, approximately 13,000 genera and 400,000 species.

The oldest, most complete flowering plant fossil, a 125-million-year-old specimen, suggests that Angiosperms may have evolved from aquatic, weedy herbs. The specimen exhibits a thin curvy stem, leaves typical of an underwater plant, a lack of flowers, and evidence of seeds enclosed within the female reproductive organs. To determine how it fit into the evolutionary family tree, researchers compared the traits evident in the fossil plant with genetic and morphological information from 173 modern flowering plants., which indicated that the specimen represents a previously unknown family, Archaefructaceae, with two species A. liaoningensis and A. sinensis considered to be a sister group to all exant angiosperms.

Basic Plant Structure

Phytomorphology (German, "study of plant shape) is the study of the physical form and external structure of plants.

Angiosperms are vascular plants. Vascular plants have three basic parts - the root, steam, and leaf.

Roots

Roots are a branched, underground structure which serves three primary functions: 1) anchor the plant, 2) absorb water and minerals for use by the plant, and 3) store food reserves. The two major types of roots are fibrous roots and taproots. Some plants have a combination of tap roots and fibrous roots.

- A taproot is a primary root that grows vertically downward and gives off small lateral roots.

- A fibrous root has many roots that grow in many directions and is usually wider than deeper.

Stems hold and provide support to the leaves and reproductive structures.

- The peduncle (Latin, “foot”) is the main stalk that holds either a single flower a complete inflorescence, a cluster, or a head, of flowers.

- The pedicel (Latin, “small foot”) is the stalk that holds an individual flower.

The top of the peduncle or pedicel forms a flat disc-like structure called the receptacle and is where the sepals, the petals, the stamens, and the pistils are attached.

Leaves occur in various types according to size, shape, color, texture, form, and other characters. The most basic form is a flat, green leaf. Leaves allow the absorption of sun light and carbon dioxide for photosynthesis and release of oxygen to the atmosphere.

John Ray (English, 1628-1705), a naturalist formulated the fundamental principles of plant classification in his landmark works “Catalogus Plantarum Angliae” (Catalog of English Plants) in 1670 and “Methodus Plantarum Nova” (A method for New Plants) in 1682. He divided plants into three groups based on seed leaf (cotyledons or embryonic seed leaves) structure:

Cryptogams, plants that reproduce by spores, without flowers or seeds.
Monocotyledons are flowering plants with a single cotyledon (seed leaf). They make up about 25% of all Angiosperm. Monocotyledons have flower parts that exist in groups or multiples of threes, narrow leaves with parallel veins, and fibrous roots. There are approximately 60,000 species of monocots, and the largest of all plant families, Orchidaceae (orchids). Other prominent monocot families include Liliaceae (lilies), Arecaceae (palms), Iridaceae (irises), and including Poaceae (grasses).
Dicotyledons (Eudicots)are flowering plants that produce two or more cotyledons (seed leaf).They make up about 75% of all Angiosperm. Dicotyledons have flower parts in groups or multiples of four or five, broad, stalked leaves with netlike veins, and tap roots. The Asteraceae flower family, which includes sunflowers and dandelions, is the largest dicot family.

There is some evidence that dinosaurs ate angiosperms. Two dinosaur coprolites (fossilized excrement) discovered in Utah contain fragments of angiosperm wood, according to an unpublished study presented at the 2015 Society of Vertebrate Paleontology annual meeting. This finding, as well as others, including an Early Cretaceous ankylosaur that had fossilized angiosperm fruit in its gut, suggests that some paleo-beasts ate flowering plants. Moreover, the shape of some teeth from Cretaceous animals suggests that the herbivores grazed on leaves and twigs.