What is a Gymnosperm?
Most gardeners are familiar with the terms gymnosperm and angiosperm, but many may not be sure exactly what the differences are. This article will concentrate primarily on introducing Gymnosperms, with a few comparative comments about angiosperms (or what are also known as flowering plants).
When I first learned the term gymnosperm, I came away with the understanding that they were basically pine trees. And indeed, pines are gymnosperms. But it turns out there are lots of trees that look to me like pine trees that are belong to a dozen or more other families of gymnosperm. And it also turns out there are many plants out there that are gymnosperms that are not conifers at all. Some of these are now among my favorite plants (namely the Cycads). And some are plants I have added to the plant files that I had no clue where not flowering plants. Every time I research an article, it turns out to be an amazing learning experience.
Ponderosa Pines are what I always considered typical Gymnosperms (left); right is my small cycad Bowenia spectabilis, a less typical Gymnosperm
In a previous article I talked about the differences between monocots and dicots, something I was pretty unclear on until I wrote the article. Neither of those terms apply to Gymnosperms as Gymnosperms do not have a ‘cot'. I was a bit surprised to learn that Gymnosperm and Angiosperm were not official designations in the taxonomic tree of life. They are more biological categories of plants, and not part of the ‘King-Phillips-Came-Over-For-Good-Soup' taxonomic categories (that phrase is a mnemonic to help students remember the basic taxonomic categories: Kingdom, Phyllum, Class, Order, Genus and Species... though it appears nowadays it is ‘Division', rather than ‘Phyllum'... so now it has to be ‘King David Came Over For Good Soup').
left- Aloe petrophila; right- Erythrina speciosa. Examples of a monocot (left) and dicot (right) Angiosperms, or flowering plants
Cedrus atlantica with female cones (photo mgarr)- left; Macrozamia pauli-guilliami female cycad cones (right)- two Gymnosperms showing reproductive structures- no flowers on these two kinds of plants.
Gymnosperms are a large group of plants that do not make flowers at all and have a unique form of reproduction. This is a very old group of plants, first showing up over three hundred million years ago. The word Gymnosperm means naked seed. Most flowering plants have their seeds inside of fruits. But there no fruits in the Gymnosperm world and the seeds are ‘naked' within cone-like structures. There is a coating surrounding each seed in some cases (like in the cycads) and this coating is sometimes referred to as the fruit, but I think that is an incorrect usage of the word fruit. The details of the pollen getting to the ‘egg' are a bit complex, but just believe me that the reproductive processes are different in Gymnosperms than in Angiosperms, and taxonomically, that is a big deal. For those who really want to know the details of their sex lives, and the triploid versus haploid situation, here are some links for you: http://www.differencebetween.net/science/nature/difference-between-angiosperms-and-gymnosperms/; http://www.differencebetween.net/science/nature/difference-between-angiosperms-and-gymnosperms/
Agathis winged seeds (left) Araucaria sp. seeds (right)
Pine cone with 'naked seeds' (left) Pine nuts (right- both photos from Wikipedia)
Gymnosperms and Angiosperms both make seeds which set them apart from another large group of even more primitive popular plants, the ferns (spore producers).
Asplenium nidus 'plicatum' or plicated Bird's Nest Fern (left) and Cyathea aramaganensis (a tree fern- right)- two examples of non-flowering but also non-Gymnosperm plants
Some generalizations: Gymnosperms do not make flowers or fruits. Most gymnosperms are trees or large shrubs. Most have needles for leaves, but the variety of needles found on gymnosperms is huge. Those not having needles generally have thick scales or leaves, most which are stiff, relatively inedible and almost plastic-like in consistency. Most Gymnosperms have recognizable male and female cones. Most are evergreens. Most are adapted to harsher climates than are the average angiosperms, some surviving extreme cold and/or extreme drought. Many gymnosperms are dioecious (separate male and female plants), but I could not say that most are, as so many conifers are monoecious (male and female cones on the same tree). There are exceptions to nearly all the above generalizations, of course.
Examples of Gymnosperm foliage:
Typical Pine needles of a Limber Pine (left) Needles of an Italian Stone Pine (photo Fruticosa)
Agathis australis leaves- very thick and plastic-like (left); Uniquely stacked, sharp, stiff leaves of Monkey Puzzle Tree, Araucaria aracana (right)
Encephalartos horridus (left)- photo Xenomorf and Encephalartos ferox (right) showing some of the many variations in cycad leaves- all are very leathery-plastic-like
Cephalotaxus harringtonia leaves (photo by growin)
Podocarpus henkii leaves (slightly more pliable, but still thick with a plastic-like surface)- left; Afrocarpus gracilis leaves right- excpetions to the rule with fairly soft leaves
Examples of Gymnosperm Cones, or reproductive structures:
Agathis robusta green cone (left) Araucaria bidwillii green cone (right)- photo ginger749
Deodar Cedar female (left) and male cones (right)- note the pollen coming from the male cone
Jeffrey's Pine cone (left photo Equilibrium); Sequoia cones (right photo Kelli)
Spruce tree cone (left) Italian Cypress cones (right)
Encephalartos ferox female (left) and male (right) cones
Welwitschia female (left) and male (right) reproductive structures
Female left and male right Gingko biloba reproductive structures (photos from Wikipedia)
Below are the major groups of Gymnosperms:
•1. Subclass Pinadae (the pines are related trees):
•A. Order Pinales- the only family in this order is Pinaceae, or what I call pine trees. These include the genus Cedrus (Cedars), Pinus (true Pine trees), Picea (trees that LOOK like pine trees but called Spruces), ), Abies (more trees that look like pines, the firs), Pseudotsuga (the Douglas Firs (also look like pine trees)), Tsuga (the Hemlocks) and a bunch of less well known genera including Nothotsuga, Cathaya, Larix (the Larches), Pseudolarix (the Golden Larch) and Keteleeria. http://en.wikipedia.org/wiki/Pinales
Cedrus deodar (Deodar Cedar) left Cedrus atlantica 'Glauca Pendula' (Weeping Blue Cedar) right
Pinus bungiana (Lacebark Pine) left Pinus canariensis (Canary Island Pine) right
Picea pungens Colorado Spruce (left) Abies bracteata (Bristlecone Fir) right
Pseudotsuga macrocarpa Big Cone Douglas Fir left; Tsuga canadensis Canadian Hemlock (photo by DaylilySLP) right
Larix lyalii Subalpine Larch (photo by altagardener) left Larix sibirica Siberian Larch (photo Equilibrium) right
•B. Order Cuppressales- these are also trees but generally with more flatten needles that could be called leaves... The big family in this order is Cuppressaceae (aka Cypress Trees) which includes 95% of all the trees in this order. The next largest family is the Taxaceae (the Yew Family) and one odd-ball family, Scadiopityaceae (a very attractive pine tree called the Japanese Umbrella Pine) http://en.wikipedia.org/wiki/Sciadopityaceae.
Cupressus cashmeriana (Kashmir Cypress) left; Cupressus sempervirens (Italian Cypress) right
Sciadopitys verticillata Japanese Umbrella Pine (right)
•a. The Cypress family is then broken up into a bunch of genera including a few unusual ones that have deciduous trees (Metasequoia (Dawn Redwood), Taxodium (Bald and Mexican Cypress) and Glyptostrobus (Chinese Swamp Cypress). Other families include Cunninghamia (Chinese Firs), Taiwania, Sequoia (Coast Redwood), Sequoiadendron (Giant Sequoia), Cryptomeria, Cupressus (true Cypress), Juniperus (the Junipers) and a bunch of other families that seem to have few common names attached to them: Athrotaxis, Callitris, Actinostrobis, Thuja (the arborvitae) etc. (see this link for more): http://en.wikipedia.org/wiki/Cupressaceae
Metasequoia glyptrostroboides (Dawn Redwoods) left: Glyptostrobus pensilis (Chinese Swamp Cypress) right (photo dwarfconifer)
Cunninghamia lanceolata glauca Chinese Blue Fir (left)- photo growin; Cunninghamia lanceolata China Fir (right)
Taxodium distichum Bald Cypress bonsai (left); Taxodium huegelii (Montezuma Cypress) right
Sequoiadendron giganteum Giant Sequoias left (photo Gustichock); Sequoia sempervirens Coast Redwood right
Juniperus scopularum 'Tollifson's Blue Weeping' Rocky Mountan Juniper (left); Juniperus communis Common Juniper right (photo Xenomorf)
Juniperus chinensis bonsai (left); Juniperus californica (right). These two are among some of the most popular of all the bonsai tree species
Taiwania cryptmerioides (left) Thuja occidentalis (American arbovitae) right (photo DaylilySLP)
•b. The Yew family includes these genera: Taxus (the real Yews), Pseudotaxis (the White-Berry Yew), Austrotaxus (the New Caledonian Yew), Torreya (Nutmeg Yew etc.), Amentotaxus and Cephalotaxus (Plum Yew). I don't have much to add on this family except to say these among the some of the most toxic of all the plants. http://en.wikipedia.org/wiki/Taxaceae
•C. a. Order Araucariales (the Araucarias and Podocarpus trees) broken into two families, Araucariaceae and Podocarpaceae. The former includes all the ancient conifers (many from Australia) including the genera Agathis, Araucaria and Wollemia (the living fossil of trees). http://davesgarden.com/guides/articles/view/1090/
Agathis robusta (left) Agathis microstachya (right)
Araucaria bidwillii Bunya Bunya (left); Araucaria columnaris Cook Pine (right)- this species is commonly sold as Norfolk Island Pine (see below)
Araucaria araucana Monkey Puzzle Tree (left); Araucaria heterophylla (the real thing) Norfolk Island Pine right
Wollemia nobilis pines for sale
b. The Podocarpaceae includes Podocarpus, Afrocarpus and a bunch of genera I am completely unfamiliar with, all native to the southern half of the world. Most of these plants are pretty rare in cultivation, but a few are extremely common landscape and street trees, at least here in southern California. http://en.wikipedia.org/wiki/Podocarpaceae
Afrocarpus gracilior East African Yellowwood- a common street tree in southern California (and elsewhere)
Podocarpus henkii (left) Podocarpus latifolius (right)
•2. Subclass Cycadidae (the cycads) with only one order, order Cycadales, which is divided into two families, Cycadaceae and Zamiaceae (see this article for more on cycads: http://davesgarden.com/guides/articles/view/41/ ). This is another highly toxic group of plants.
Cycas revolutas (Sago Palms) in California - this cycad is the family Cycadaceae
Encephalartos altensteinii (in the family Zamiaceae) (left); Ceratozamia whitelockiana right (another Zamiaceae)
Zamia furfuracea (aka Cardboard Palms)- left, and Macrozamia fraseri (right) are two more examples of cycads in the family Zamiaceae
Cycads in Santa Barbara's Lotusland- almost all in photo in family Zamiaceae
•3. Subclass Ginkgoidae, which not only has one order, Ginkgoales, but only one species, Ginkgo biloba, the common street tree and natural herbal remedy for memory loss. http://en.wikipedia.org/wiki/Ginkgoaceae
Gingko biloba tree in fall (one of the deciduous gymnosperms)
•4. Subclass Gnetidae divided up into three small Orders
•A. Order Ephedrales- the Ephedras, some of which are common southwest US native shrubs I had no idea where gymnosperms. As the name suggests, this is where Ephedra, the drug, comes from. The common names for these plants includes Mormon-tea and Mahuang.
Ephedra nevadensis Mormon Tea
Ephedra male 'cones' (left) and female cones (right) both photos Wikipedia
•B. Order Welwitschiales- an order with only one species, Welwitschia mirabilis, a bizarre by treasured plant of Namibia with only two leaves that grow for many centuries. This plant lives in the arid desert out in the middle of nowhere.
Welwitchia mirabilis in cultivation
•C. Last, but maybe not least, Gnetales, a whole order in which I know little and containing a single genus with about 30 species of rarely grown tropical plants. For more on this oddball group of plants, see this link: http://en.wikipedia.org/wiki/Gnetophyta
photo from Wikipedia