Bot-Lec (Sem-1) - Chapter 9: Gymnosperms

seed

a reproductive body consisting of a young, multicellular plant and food reserves, enclosed by a seed coat (testa); reproductively superior to spores

radicle; cotyledon; testa; arils; embryo; haploid gametophyte

parts of a gymnosperm seed

radicle

part of a gymnosperm seed; embryonic root

cotyledon

part of a gymnosperm seed; embryonic leaves

testa

part of a gymnosperm seed; seed coat; parental sporophyte tissue

aril

part of a gymnosperm seed; an extra seed-covering, typically colored and hairy or fleshy

embryo

part of a gymnosperm seed; daughter sporophyte (diploid)

haploid gametophyte

part of a gymnosperm seed; food supply

scale

part of a pine cone; from where the ovules (which develop into seeds) are borne

spores

a single cell with minimal food reserves to sustain the plant that develops from a germinating spore

ovule

structure in seed plants that develops into a seed following fertilization

integument

outer layer of an ovule that develops into a seed coat following fertilization

gymnosperm

any of a group of seed plants in which the seeds are not enclosed in an ovary; seeds are either totally exposed or borne on scales of cones; produce wind-borne pollen grains

Taxus baccata

European yew/yew berries; gymnosperm that is often mistaken for an angiosperm due to the fleshy aril of the seeds

pollen grain

structure in seed plants that develops from a microspore into a male gametophyte

coniferophyta (conifers); cycadophyta (cycads); ginkgophyta (ginkgoes); gnetophyta (gnetophytes)

four phyla of gymnosperms

coniferophyta (conifers)

woody trees and shrubs with needlelike, mostly evergreen leaves, and seeds in cones; mostly monoecious; the most predominant trees (about 35% of the world’s forests)

strobilus

an aggregation of sporophylls resembling a cone (as in the club mosses and horsetails)

evergreen

a plant which has foliage that remains green and functional throughout the year

Pinus longaeva

conifer; bristlecone pine; one of the longest-living species of tree on Earth (world record: approx. 5,000 years old)

Picea pungens

conifer; Colorado blue spruce

Abies concolor

conifer; white fir

Pinus strobus

conifer; white pine; leaves are long, slender needles that occur in clusters of five

Thuja occidentalis

conifer; American arborvitae; leaves are small and scale-like

Pseudotsuga menziesii

commercially important conifer; Douglas fir; grows along the Pacific coast and in the Rocky Mountains

Picea rubens

commercially important conifer; red spruce; found in eastern Canada and the northeastern United States (also extends southward to the Great Smoky Mountains)

Pinus taeda

commercially important conifer; loblolly pine; widely distributed through the southeastern United States

cycadophyta (cycads)

palm-like or fern-like in appearance; pollen and seeds in cone-like structures; relatively few living members; dioecious

Encephalartos transvenosus

cycad; Modjadji’s palm/cycad; localized distribution in South Africa; grows to approx. 9.2 meters (30 feet) and resembles a palm

Zamia integrifolia

cycad; coontie/sago cycas; native to southeastern United States, the Bahamas, Cuba, the Cayman Islands, and Puerto Rico; usually short (under 2 meters tall)

ginkgophyta (ginkgoes)

has only one surviving species; deciduous; produce fleshy seeds directly on branches; dioecious

deciduous

a tree or shrub that sheds its leaves annually

Ginkgo biloba

ginkgo; maidenhair tree; only surviving species of phylum ginkgophyta;

gnetophyta (gnetophytes)

share traits with angiosperms; more efficient water-conducting cells (vessel elements) in xylem; mostly dioecious

Gnetum gnemon

gnetophyte; melinjo/bago; resemble flowering plants due to fleshy exposed seeds that are yellow to red when ripe

Ephedra

gnetophyte; jointfir; pollen clones cluster at nodes; European pioneers used species native to the American southwest to make Mormon tea

Welwitschia

gnetophyte; tree tumbo; native to deserts in southwestern Africa; survives on moisture-laden fogs that drift inland from the ocean

monoecious

having male and female reproductive parts in separate flowers or cones on the same plant

dioecious

having male and female reproductive structures on separate plants

sporpohyte

usually dominant; the diploid multicellular stage in the life cycle of a plant or alga which produces asexual haploid spores that develop into a gametophyte; e.g. pine tree

gametophyte

the gamete-producing and usually haploid phase, producing the zygote from which the sporophyte arises; the dominant form in bryophytes

pine gametophytes

extremely small and nutritionally dependent on sporophyte generation

heterosporous

the production of two types of spores (microspores; megaspores); e.g. pine

sporophyll

leaflike structure that bears spores within a sporangium (or sporangia)

microspores

produced by male cones; develop into pollen grains, which are carried by air currents to female cones

megaspores

produced by female cones; one of four produced by meiosis develops into a female gametophyte within an ovule

pollination

the transfer of pollen to female cones

pollen tube

after pollination; a tube that forms after the germination of a pollen grain and through which male gametes (sperm cells) pass into the ovule; grows through the megasporangium to the egg within the archegonium

watershed

an area of land that drains all the streams and rainfall to a common outlet

amber

fossil tree resin that has achieved a stable state through loss of volatile constituents and chemical change after burial in the ground; mostly produced by conifer trees

progymnosperms

seedless vascular plants that had megaphylls and “modern” woody tissue; probably gave rise to conifers and seed ferns, which likely gave rise to cycads and ginkgo

Archaeopteris

progymnosperm; existed about 370 mya; had some features in common with modern seed plants but did not produce seeds

Emplectopteris

seed fern; produced seeds on fernlike leaves; seed ferns existed from about 360 mya to 250 mya