Arboretum Images 4

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Palomar College Arboretum Images 4: Conifers #1

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Araucaria Family (Araucariaceae)

 		The araucaria family (Araucariaceae) includes some of the most remarkable conifers on earth. They are tall trees native to forested regions of South America and Australia. In majestic size and beauty, they certainly rival the coniferous forests of North America and Eurasia. In fact, they are considered the southern counterpart of our northern pine forests. Fossil evidence indicates that ancestral araucaria forests date back to the age of dinosaurs. Baltic amber, the European gemstone called jet, and the magnificant trees of Petrified Forest National Park in Arizona all came from ancient forests of this plant family. The left image is a Norfolk Island pine (A. heterophylla) that grows near the entrance to the Arboretum. It is easily recognized by its horizontal tiers of spreading branches.
The Araucariaceae contains three remarkable genera of cone-bearing trees: Araucaria, Agathis and Wollemia. The type genus Araucaria is derived from "Arauco," a region in central Chile where the Araucani Indians live. This is also the land of the "monkey puzzle" tree (A. araucana), so named because the prickly, tangled branches would be difficult for a monkey to climb. Fossil evidence indicates that ancestral araucaria forests resembling the present-day monkey puzzle date back to the age of dinosaurs. In fact, it has been suggested that the tree's armor of daggerlike leaves was designed to discourage enormous South American herbivorous dinosaurs, such as Argentinosaurus weighing an estimated 80 to 100 tons! Another ancient South American species called pino paraná or paraná pine (A. angustifolia) grows in southern Brazil and Argentina. Three species of Arucaria are shown in the image to the right.

A South American monkey puzzle tree (Araucaria araucana). The prickly, tangled branches would probably be difficult (and painful) for a monkey to climb. Fossil evidence indicates that ancestral araucaria forests resembling the present-day monkey puzzle date back to the age of dinosaurs.

Close-up view of the dense, sharp-pointed leaves of the monkey puzzle tree (Araucaria araucana). This species does not grow well in southern California, but forms beautiful specimen trees in the Pacific northwest and England. An ancestral species formed extensive forests in Europe during the Jurassic Period, about 150 million years ago.

Left: The Australian Bunya-Bunya tree (Arauacaria bidwillii). Right: Cook Pine (A. columnaris) or possibly a hybrid with the Norfolk Island pine (A. heterophylla). The Cook Pine is naturalized throughout the Hawaiian Islands and has a slender, spirelike crown. The name A. excelsa has been used incorrectly for the Cook Pine and Norfolk Island pine.

The slender, spirelike crowns of Cook pine (Araucaria columnaris) form a striking contrast with the rugged mountains of Kauai, Hawaii. Cooks pines are native to New Caledonia and were introduced throughout the Hawaiian islands.

Branchlets of three South Pacific species of Araucaria native to Norfolk Island and Australia. Although they are called "pines," they do not belong to the pine family (Pinaceae). Unlike the long, slender needles of pines, araucarian leaves are usually short, overlapping and often prickly. Top: Norfolk Island pine (A. heterophylla) with dense, overlapping, awl-shaped leaves. Middle: Hoop pine (A. cunninghamii) with flattened, needlelike leaves. Bottom: Bunya-bunya pine (A. bidwillii) with broad, sharp-pointed leaves.

Hoop pine (Araucaria cunninghamii). The bark spits horizontally at regular intervals into rings or hoops. This is the derivation of the common name "hoop pine."

Hoop pine (Araucaria cunninghamii). The bark spits horizontally at regular intervals into rings or hoops. This is the derivation of the common name "hoop pine."

Left: A Brazilian or Parana pine (Araucaria angustifolia) with an A. columnaris x A. heterophylla hybrid in the distance. Right: A green branchlet of A. bidwillii (left) compared with a dried branchlet and male cones of the Brazilian pine (A. angustifolia).

Left: A cone-bearing branch from the Norfolk Island pine (Araucaria heterophylla), a close relative of the Cook pine (A. columnaris). The branches of both species are densely clothed with small, overlapping, triangular leaves. Right: A cone-bearing branch from the dammar pine or Queensland kauri (Agathis robusta), another interesting Australian member of the Araucariaceae. The leaves of this species are unusual among conifers because they are broad-leaved rather than needlelike or scalelike.

Bunya-Bunya: One Of The Largest Seed Cones Produced By A Conifer

Bunya-bunya cone (Araucaria bidwilii) compared with a pineapple.

A petrified ovulate cone of Araucaria (probably A. mirabilis) from Patagonia, Argentina. This extinct species of Araucaria dates back to the Jurassic Period (135-180 million years ago), when giant dinosaurs ruled the earth. Although prickles on the cone scales have worn away after millions of years of erosion, the cone is remarkably preserved. The right view clearly shows one seed per scale (black arrow), typical of modern-day species of Araucaria, such as the Norfolk Island Pine.

  More Information & Images About The Araucaria Family  

Cypress Family (Cupressaceae)

Update On The Taxonomy Of Cypresses (Cupressus)

Just when I think I have a handle on the taxonomy of cypresses (Cupressaceae), new research emerges from the amazing field of DNA phylogeny and cladistic analysis. Early in this century, a new cypress species was discovered in Vietnam. It was named Xanthocyparis vietamensis. [The name Cupressus vietnamensis also appears in some garden references.] Surprisingly enough, its closest relative was found to be the Alaska cedar (Chamaecyparis nootkatensis syn. Cupressus nootkatensis), separated by thousands of miles and on opposite sides of the Pacific Ocean. The two species were so similar that the authors (Farjon et al 2002), working in Kew, England, combined them generically, and the Alaska cedar became Xanthocyparis nootkatensis. Port Orford cedar (Chamaecyparis lawsoniana) resembles other North American and Asian species of Chamaecyparis in both morphology and DNA, so its scientific name remains unchanged.

The Alaska cedar is the only Chamaecyparis species that forms spontaneous, fertile hybrids with Cupressus species when these are grown together in botanical gardens. Evidence from DNA and morphology indicates that it and the Vietnam cypress are closely related phylogenetically to the New World species of Cupressus (Little et al, 2004). The Old World species of Cupressus, however, are a separate evolutionay line, as is the large genus Juniperus. True Chamaecyparis species are only distantly related to the cluster genera that includes Old World Cupressus, Juniperus, Xanthocyparis, and New World Cupressus. In a comprehensive study, Little, D.P. (2006) proved that the Alaska Cedar and its Vietnam relative should be placed in the same genus as the New World Cupressus, but that the correct generic name for this group is Callitropsis. His study incorporated 88 morphological and wood-chemistry characteristics in 56 species of Cupressaceae, combined with sequence analysis of three chloroplast genes and two nuclear genes. The name Cupressus technically only applies to the Old World species in this genus. It turns out that Callitropsis nootkatensis was used for the Alaska cedar in 1864, long predating the name Xanthocyparis. In accordance with the Botanical Rule of Priority, the older name must be used. Therefore, Alaska cedar becomes Callitropsis nootkatensis, Vietnam cypress becomes Callitropsis vietnamensis, and the Alaska cedar-Monterey cypress hybrid becomes Callitropsis x leylandii. Damon Little (2006) also proposed that all of the New World Cupressus be placed in the genus Callitropsis. The latter genus superficially resembles the Australian genus Callitris.

Based on their general morphological appearance, the New World Cupressus certainly resemble Old World Cupressus species; however, this similarity may be due to parallel evolution (homoplasy) in similar warm, dry climates. Just because these two groups of cypress appear similar doesn't necessarily mean that they are all closely related members of the same genus. DNA comparisons appear to reflect their true genetic affinities and differences. Groupings of species, such as Callitropsis, Chamaecyparis, Juniperus and Old World Cupressus represent separate branches (clades) in computer-generated phylogenetic trees.

Using DNA to Compare Genera & Species
Homoplasy: Parallel and Convergent Evolution
  Representatives of the Taxodium Family (Taxodiaceae)  

Two species of Australian cypress pines (Callitris): A. Callitris preissii (C. robusta) and B. Callitris columellaris. Their foliage and seed cones greatly resemble our North American cypress (Cupressus). The large boulders contain colonies of the black crustose lichen Verrucaria nigrescens.

  Black Crustose Lichens In The Palomar College Arboretum  

Left: Tolleson's blue weeping juniper (Juniperus scopulorum 'tolleson's weeping' ). The seed cones of junipers are fleshy, compared with the woody cones of Cupressus. Right: Mexican cypress (Cupressus lusitanica). Note: Based on DNA evidence, the generic name Callitropsis has been proposed for New Word species of Cupressus.

Seed cones from cypress groves in California, Arizona and outside the U.S.

A. Tecate cypress (C. forbesii), B. Sargent cypress (C. sargentii), C. Piute cypress (C. nevadensis), D. Cuyamaca cypress (C. stephensonii), E. Santa Cruz cypress (C. abramsiana, F. Monterey cypress (C. macrocarpa), G. Gowen cypress (C. goveniana), H. Mendocino cypress (C. pygmaea), I. Macnab cypress (C. macnabiana), J. Modoc cypress (C. bakeri), K. Smooth-bark Arizona cypress (C. glabra), L. Rough-bark Arizona cypress (C. arizonica), M. Italian cypress (C. sempervirens), N. San Pedro Martir cypress (C. montana), O. Mexican cypress (C. lusitanica), P. Sahara cypress (C. dupreziana), Q. Kashmir cypress (C. cashmeriana), R. Mourning cypress (C. funebris), S. Port Orford cedar (C. lawsoniana), T. Alaska cedar (C. nootkatensis), U. Leyland cypress (x Cupressus leylandi).

Note: The Port Orford cedar (S) and Alaska cedar (T) are often placed in the genus Chamaecyparis, while the Leyland cypress (U) is placed in the genus Cupressocyparis.

  Cupressus: Remarkable Conifers Native To California
   Selection & Genetic Drift In Cypresses (Cupressus)

Podocarpus Family (Podocarpaceae)

Podocarpus gracilior, a member of the Podocarpaceae native to eastern Africa. Although it is sometimes called "fern pine" it does not belong to the genus (Pinus); however, like pines and other cone-bearing species, it does belong to the division Coniferophyta. Small female cones are composed of 2-4 reduced scales, but usually only one scale bears an ovule that matures into a seed. There is little resemblance to a cone in the mature seed. The seed has a hard coat surrounded by a fleshy outer layer (aril). The drupelike seed often sits on a fleshy red or purple base or cone axis that is called an aril in some references. The seeds are similar to the California nutmeg (Torreya californica) and Pacific yew (Taxus brevifolia), members of the closely-related yew family (Taxaceae). In the latter species, the naked seed sits partially exposed in a red, cup-shaped aril. Podocarpus seeds are often referred to as fleshy fruits called drupes, but this is incorrect because drupes develop from the ovaries of flowering plants. Another group of conifers with fleshy seed-bearing structures are the junipers (Juniperus) in the cypress family (Cupressaceae). Junipers actually produce small cones with fleshy, fused scales bearing one-several seeds. Podocarpus is a dioecious species, with separate male and female trees in the population. Podocarpus has an ancient lineage dating back to distant relatives that lived during the Jurassic Period 170 million years ago.

  Calif. Nutmeg (Torreya) and Pacific Yew (Taxus) in the Taxaceae  
Calif. Nutmeg (Torreya californica) in Sequoia Nat. Park
See the Pacific Yew (Taxus brevifolia) in Montana   

Cycad Family (Zamiaceae)

Male cones of Zamia furfuracea, an interesting cycad native to eastern Mexico. Like some of the other species in this genus, the main trunk is partly or completely subterranean with leaves arising from near the ground level. The cone scales have pollen-bearing sporangia on their underside. After landing on the scales of receptive female (ovulate) cones, the grains develop into pollen tubes that grow toward the egg-bearing ovules. The multiciliate sperm of Zamia species are some of the largest in the world, and in Z. roezlii they are actually visible to the naked eye. Several species of Zamia are native to the southeastern United States (mainly Florida), including Z. integrifolia, Z. floridana and Z. pumila, although some of these may only be variants of Z. integrifolia. The starchy pith of Florida cycads was collected by Seminole Indians and used to make a type of bread. It is known as sago starch or Florida arrowroot. Although once common in their natural habitats, the native populations of these species have been greatly reduced due to poaching and overcollecting. Some of these species are commonly cultivated in southern California, especially in tubs and planter boxes with well-drained soils.

  Cycads That Lived With Dinosaurs  
Cycads: Plants Of Jurassic Park
Cycads & Continental Drift
Plants Of Jurassic Park

References

  1. Armstrong, W.P. 1978. "Southern California's Vanishing Cypresses." Fremontia 6 (2): 24-29.

  2. Armstrong, W.P. 1977. "The Close-Cone Pines and Cypresses" (Chapter 9, pp. 295-358). In: Terrestrial Vegetation of California, John Wiley & Sons.

  3. Armstrong, W.P. 1966. Ecological and Taxonomic Relationships of Cupressus in Southern California. MA Thesis, Biological Science Department. California State College at Los Angeles.

  4. Farjon, A. et al. 2002. "A New Genus and Species in the Cupressaceae (Coniferales) from Northern Vietnam, Xanthocyparis vietnamensis." Novon 12: 179-189.

  5. Griffin, J.R. and W.B. Critchfield. 1972. The Distribution of Forest Trees in California. USDA Forest Service Research Paper PSW 82. Berkeley, California.

  6. Hickman, J.C. (Editor). 1993. The Jepson Manual: Higher Plants of California. University of California Press, Berkeley.

  7. Lanner, R.M. 1999. Conifers of California. Cachuma Press, Los Olivos, California.

  8. Little, D.P. et al. 2004. "The Circumscription and Phylogenetic Relationships of Callitropsis and the Newly Described Genus Xanthocyparis (Cupressaceae)." American Journal of Botany 91: 1872-1881.

  9. Little, D.P. 2006. "Evolution and Circumscription of the True Cypresses (Cupressaceae: Cupressus)." Systematic Botany 31: 461-480.

  10. Little, E.L., Jr. 1953. Check List of Native and Naturalized Trees of the United States. USDA Forest Service Agriculture Handbook No. 41, Washington, D.C.

  11. Wolf, C.B. 1948. "Taxonomic and Distributional Studies of the New World Cypresses." El Aliso 1: 1-250.