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Phylum Pinophyta
Phylum Pinophyta
The conifers are cone-bearing gymnosperms that are most-frequently evergreen trees, but some are deciduous (e.g. Taxodium, Larix). Conifers dominate in taiga biomes, as well as temperate areas with poor soils. Most polar, and many temperate, conifers have a pyramid shape with weak branches: an adaptation to shed snow. In addition, conifers have many adaptations to survive in cold, dry conditions: needle-like leaves, hypodermis in leaves, sunken stomata, narrow xylem cells, and resin canals to name some. Conifer evergreens are sometimes referred to as "softwoods" because they have wood that is light-weight, weak in shear (along the grains), but strong in tension. It is usually light in color and cheaper, therefore used for building inexpensive furniture or used for paper pulp.
The conifers include some of the most extreme organisms on Earth: the tallest organisms (i.e. Sequoia sempervirens), the heaviest (non-clonal) organisms (i.e. Sequoiadendron giganteum), the oldest (non-clonal) organism (i.e. Pinus longaeva), and the widest (non-clonal) plants on Earth (i.e. Taxodium mucronatum).
Diversity
Diversity
Conifers represented by 7 extant families, 66 extant genera, and ~589 species
This is the largest diversity of gymnosperms
Conifers dominate in the taiga biome
Classification
Classification
└Tracheophytes
└Euphyllophytes
└Lignophytes
└Spermatophytes
└Pinophyta
└Pinopsida
└Pinales
Geologic Range
Geologic Range
Triassic - present
Seed-bearing phase (=sporophyte)
Seed-bearing phase (=sporophyte)
Vegetative features
Vegetative features
Stems
All conifers are woody; usually trees
Stems exhibit eustele with 2-faced (bifacial) cambium
Pycnoxylic wood: Wood made mostly of tracheids but little parenchyma
Leaves
Leaves tend to be needle-shaped, scale-like, or awl-shaped
Parallel veins
Most evergreen; few deciduous in wetlands (e.g. Taxodium, Larix)
Conifers exhibit xeric leaf adaptations (e.g. sunken stomata; hypodermis, reduced surface area)
Reproductive features
Reproductive features
Mostly monoecious
Differentiated male and female cones
Female cone, called the megasporangiate cone
Large and woody
Cones are "compound"; modified stems hold ovules
These modified stems are called ovuliferous scales
Ovules attached to scale in various orientations
Each scale is subtended by a modified leaf (bract)
Male cones, called the microsporangiate cone
Smaller in size than female cones
Cones are "simple"; modified leaves hold the pollen sacs
Above: longitudinal section through a seed cone of Pinus
Above: a few ovuliferous scales with ovules, from a female cone of Pinus
Above: longitudinal section through a pollen cone of Pinus
Above: a few microsporophylls with pollen sacs (microsporangia) filled with pollen, from a male Pinus cone
Family Pinaceae
Family Pinaceae
e.g. pines, fir, hemlock
Abies, Cathaya, Cedrus, Keteleeria, Larix, Nothotsuga, Picea, Pinus, Pseudolarix, Pseudotsuga, Tsuga
Family Cupressaceae
Family Cupressaceae
Cypresses, redwoods
Largest of the conifer families
Actinostrobus, Athrotaxis, Austrocedrus, Callitris, Calocedrus, Chamaecyparis, Cryptomeria, Cunninghamia, Cupressus, Diselma, Fitzroya, Glyptostrobus, Juniperus, Libocedrus, Metasequoia, Microbiota, Neocallitropsis, Papuacedrus, Platycladus, Sequoia, Sequoiadendron, Taiwania, Taxodium, Tetraclinis, Thuja, Thujopsis, Widdringtonia
Family Podocarpaceae
Family Podocarpaceae
e.g. Buddhist pines
Acmopyle, Afrocarpus, Dacrycarpus, Dacrydium, Falcatifolium, Halocarpus, Lagarostrobos, Lepidothamnus, Manoao, Microcachrys, Microstrobos, Nageia, Parasitaxus, Phyllocladus, Podocarpus, Prumnopitys, Retrophyllum, Saxegothaea, Sundacarpus
Family Cephalotaxaceae
Family Cephalotaxaceae
e.g. plum yews (this family may be included in Taxaceae)
Family Sciadopityaceae
Family Sciadopityaceae
Sciadopitys (S. verticillata is the only species)
Family Taxaceae
Family Taxaceae
Yews
Additional Resources
Additional Resources
Scientists cast doubt on study claiming trees 'talk' before solar eclipses (LiveScience 13May2025)
└Chiolerio et al. (2025) Bioelectrical synchronization of Picea abies during a solar eclipse
The science behind Christmas trees: How conifers brave winter's worst (Phys.org 20Dec2024)
└Bag et al. (2024) Photosynthetic advantages of conifers in the boreal forest
Ancient pines could reveal the heat of thousands of past seasons (Phys.org 6Aug2024)
└Mil et al. (2024) Bristlecone Pine Maximum Latewood Density as a Superior Proxy for Millennium-Length Temperature Reconstructions
Hidden giants: how the UK’s 500,000 redwoods put California in the shade (The Guardian 16Mar2024)
Giant sequoias are a rapidly growing feature of the UK landscape (Phys.org 12Mar2024)
└Holland et al. (2024) Giant sequoia (Sequoiadendron giganteum) in the UK: carbon storage potential and growth rates
'Living fossil' tree frozen in time for 66 million years being planted in secret locations (LiveScience 28Feb2024)
Evergreens with smaller leaves offer better air pollution mitigation (Phys.org 16Jan2024)
└Barwise et al. (2024) A trait-based investigation into evergreen woody plants for traffic-related air pollution mitigation over time.
Ancient redwoods recover from fire by sprouting 1000-year-old buds (Science 1Dec2023)
└Peltier et al. (2023) Old reserves and ancient buds fuel regrowth of coast redwood after catastrophic fire.
The Wollemi pines, the "Pinosaur" (In Defense of Plants 9Oct2022)
In California, Where Trees Are King, One Hardy Pine Has Survived for 4,800 Years (NY Times 8Oct2022)
Southern conifers: meet this vast group of ancient trees with mysteries still unsolved (The Conversation 9Aug2022)
Fossils show 66 million years of insects eating Kauri trees (Phys.org, 25Nov2020)
└Donovan et al. (2020) Persistent biotic interactions of a Gondwanan conifer from Cretaceous Patagonia to modern Malesia.
Argentine fossils uncover history of celebrated conifer group (Phys.org, 18Jun2020)
└ Rosetto-Harris et al. (2020) Eocene Araucaria Sect. Eutacta from Patagonia and floristic turnover during the initial isolation of South America
Firefighting mission to save the Wollemi Pines (Sydney Morning Herald, January 2020)
Phyllocladus: The celery-topped conifers (In Defense of Plants Jan. 21, 2019)
The life cycle of the conifer (YouTube 2013)
How One Man Accidentally Killed the Oldest Tree Ever (Smithsonian 2012)
The story of Wollemia (Paleoplant Blog, Jan 2009)
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