Culturally Significant Plants

Culturally Significant Plants

Plants are often used as a tool for ceremonial purposes, as artistic media to express indigenous traditions, or as herbal remedies or hallucinogenics to fulfill cultural needs and expectations. Culturally significant plants grow on all continents and are used by all ethnicities.

Historically, humans have appropriated plants for numerous cultural applications. Since prehistoric times, plants have served as symbolic organisms to represent aspects of the life cycle and seasonal changes, to worship, and to make offerings to gods. Plants were incorporated into mythology and legends to show their meanings to various cultures.

Ethnobotany

American Indians are an example of a historic ethnic group which selected specific plant species for cultural uses, such as rituals and ceremonies.

Cycads and Palms

Cycads and Palms

Members of the phylum Cycadophyta, cycads are descendants of giant, prehistoric seed-bearing, nonflowering plants that thrived when dinosaurs lived. Palms are flowering plants with primitive origins that share characteristics with cycads but are not related to them.

Cycadophyta is one of the four phyla of gymnosperms in the kingdom Plantae. At one time, cycads grew on every continent. Fossil cycads have been located in areas where no modern cycads grow, such as Antarctica and Europe, suggesting that those places once had milder temperatures.

Origins and Habitat

The oldest cycad fossils are 245 to 208 million years old, from the Triassic period. The first cycads are believed to have appeared in the Permian period 270 million years ago. Some botanists hypothesize that cycads originated as progymnosperms in the Devonian period about 408 million to 360 million years ago.

Cytoplasm

Plant cell

The cytoplasmis defined as all of the living matter within the plasma membrane of a cell, except for the nucleus, which is isolated from the cytoplasm by the nuclear envelope.

The cytoplasm, bounded by the plasma membrane, is composed of fluid called the cytosol in which floats a large variety of molecules and molecular assemblages, ribosomes (responsible for polypeptide synthesis), and a variety of other structures called organelles (literally meaning “little organs”).

Numerous biochemical processes occur in the cytosol, including protein synthesis (translation) and glycolysis.

Cytoskeleton

Cytoskeleton

The cytoskeleton is a complex network of fibers that supports the interior of a cell. Cross-linked by molecular connectors into systems that support cellular membranes, it holds internal structures, such as the nucleus, in place and controls various kinds of cell movement.

Virtually all eukaryotic cells, including plant cells, have a cytoskeleton. Cytoskeletal systems extend internally from the membrane covering the cell surface to the surface of the membrane system surrounding the cell’s nucleus. There are indications that a cytoskeletal support system reinforces the interior of the nucleus as well.

The fibers of the cytoskeleton also anchor cells to external structures through linkages that extend through the surface membrane. The cytoskeletal material, rather than being fixed and unchanging, varies in makeup and structure as cells develop, move, grow, and divide.

Cytosol

Cell

Within each eukaryotic cell are a number of distinct, membrane-bounded structures, generically called organelles, including the nucleus, mitochondria, the endoplasmic reticulum, and chloroplasts (only found in plants, algae and some protists).

Each organelle is a specialized structure that performs a specific function for the cell as a whole. The rest of the cell, excluding the organelles, cell wall, and plasma membranes, is called the cytosol: the fluid mass that surrounds and provides a home for the organelles.

The cytosol is organized around a framework of fibrous molecules and protein filaments that constitute the cytoskeleton. Although the cytosol consists mostly of water, it contains many chemicals that control cell metabolism, including signal transmission and reception, cellular respiration, and protein transcription factors.

Deforestation

Deforestation

Deforestation is the loss of forestlands through encroachment by agriculture, industrial development, nonsustainable commercial forestry, or other human as well as natural activity.

Concerns about deforestation, particularly in tropical regions, have risen as the role that tropical forests play in moderating global climate has become better understood.

Environmental activists decried the apparent accelerating pace of deforestation in the twentieth century because of the potential loss of wildlife and plant habitat and the negative effects on biodiversity.

Dendrochronology

Dendrochronology

Dendrochronology is the science of examining and comparing growth rings in both living and aged woods to draw inferences about past events and environmental conditions.

In forested regions with seasonal climates, trees produce a growth ring to correspond with each growing season. At the beginning of the growing season, when conditions are optimum, the vascular cambium produces many files of large xylem cells that form wood.

As the conditions become less optimal, the size and number of cells produced decreases until growth stops at the end of the growing season. These seasonal differences in size and number of cells produced are usually visible to the unaided eye.