Part 1: Greenhouse 2
1. Psilotum nudum — whisk fern (Psilotaceae)
This genus is one of only two genera in the once-recognized phylum Psilotophyta. It best represents what some of the first vascular land plants in the Devonian would have look like, with green, dichotomously branching stems, no leaves, and naked sporangia (spore producing structures). Recent molecular evidence suggests, however, that Psilotum is not as primitive as most people believed and is simply a reduced fern.
2. Pisonia
umbellifera — bird-lime tree (Nyctanginaceae)
This tree is widely distributed throughout the world and found on many islands including Hawaii, Malaysia, Indonesia, and Australia. The fruits are extremely sticky and easily become attached to bird feathers and feet. This aids the tree in long distance dispersal, hence its wide geographical range.
Greenhouse 6 (Cool House)
3. Wollemi nobilis — Wollemi pine (Araucariaceae)
Not a true pine, this monotypic genus was discovered in 1994 in the Blue Mountains of Australia. DNA evidence has confirmed its placement in the Araucariaceae, as sister to the genus Agathis. The only other genus in the family, Araucaria, is found in Australasia and South America; a Gondwanan distribution.
4. Marchantia polymorpha — liverwort (Phylum Hepaticophyta)
An example of what the earliest land plants might have looked like. Fossils from the Ordovician and early Silurian indicate that non-vascular liverworts are the first recognizable land plants. Liverworts are now placed in their own phylum as DNA evidence indicates that liverworts are the first diverging lineage of extant land plants.
Greenhouse 4 (Tropical House with pond)
5. Dioon, Zamia, Cycas — cycads (Phylum Pinophyta or Cycadophyta)
Cycads are a relictual group of gymnosperms once much more prominent in the Earth's flora (Triassic & Jurassic) where they co-existed with dinosaurs. Many species today are very local endemics and critically endangered. The flat leaves of cycads have given rise to false accounts of angiosperm fossils well before the Cretaceous.
6. Fern sp. — ferns (Phylum Pteridiophyta)
Ferns are incredibly great dispersers to islands due to their small, air-borne spores. Some of the first colonists of Krakatau were ferns. Ferns represent a larger than expected proportion of the Hawaiian flora, although they show considerably less endemism. Examine the great diversity in frond (leaf) morphology of the species on these tables.
Greenhouse 5 (Begonia House)
7. Navia sp. — a bromeliad (Bromeliaceae)
Closely related to Brocchinia, and also found on tepui summits of the Guayana Highlands, this genus is more species rich with over 100 described taxa. It has apparently speciated not via “adaptive radiation” but rather through its lack of dispersablity (different populations on tepui summits become isolated and diverge from one another).
Greenhouse 8 (Tropical High House)
8. Cocos nucifera — coconut (Arecaceae)
The coconut palm is the only species in the genus Cocos, and is a large palm, growing to 30 m tall. The coconut has spread across much of the tropics, probably aided in many cases by seafaring people. In the Hawaiian Islands, the coconut is regarded as a Polynesian introduction.
Greenhouse 7 (Desert House)
9. Kalanchoe tomentosa — panda plant (Crassulaceae)
This spectacular genus of succulents exhibits a multitude of forms surpassed in the family only by Crassula (jade plant). The genus is found throughout southern and eastern Africa, into Arabia, India, and China. The majority of the diversity (70+ taxa) is found in Madagascar, where almost all native species are endemic. An example of a true adaptive radiation there, species are found in dry forests, rainforests, montane forests, and grasslands. The African and Asian species are fairly similar in growth form to one another. However, in Madagascar there are epiphytes, a geophyte, climbers, twiggy shrubs, single-stemmed plants, and small trees (the largest in the family). Many species produce plantlets along their leaf edges (seen around this specimen) that fall off and grow into new plants. As a result, these species are pernicious weeds in tropical areas such as South America, Florida, and Hawaii.
10. Metasequoia glyptostroboides — dawn redwood (Taxodiaceae)
This tree is a “living fossil” in the sense that fossils of the genus had been collected (though misinterpreted as Sequoia or Taxodium) long before the living plant was discovered in China in 1941. Though now narrowly endemic to a small area of central China, fossils are known from the Tertiary of Europe, Greenland and the United States, as well as Asia. Compare this plant to Sequoia, which has a similar paleo-distribution but is now confined to coastal northern California. Although its leaves resemble those of an evergreen tree (like Sequoia) it is actually deciduous, dropping whole "twigs" of leaves in the fall..
11. Liriodendron tulipifera — tulip tree (Magnoliaceae)
This species and L. chinense, the only other species in the genus, form one of the most famous Eastern Asia - Eastern North America disjunctions. Unmistakable Tertiary fossils of the genus are known from the western U.S., Greenland, Iceland, and continental Europe. Although these species must have been out of genetic contact for well over 10 million years, artificial hybrids have been made. The tulip tree is characteristic of the mixed mesophytic forests to the south and east of Wisconsin.
12. Ginkgo biloba — ginkgo (Ginkgoaceae)
Ginkgo has an extensive fossil record first known from the Jurassic (180mya) and still extant in the western United States into the Miocene and in Europe as late as the Pliocene. Long thought to be extinct in the wild, apparently natural populations of this tree have recently been discovered in eastern China. A recent phylogeographic study suggests two areas of Pleistocene refuge in China. The Botany Garden has a pair of Ginkgo trees, male and female.
13. Magnolia sp. — magnolia (Magnoliaceae)
Long thought to be the most primitive of flowering plants, molecular studies have identified other, more ancient groups of angiosperms. The fossil record for Magnolia stretches back almost 100 million years. During the middle of the tertiary (30-40 mya), when a continental sea covered large portions of what is now the Midwest, magnolias were found as far northwest as Wyoming. Magnolias are a classic example of the Arcto-Tertiary disjunct pattern, being found in eastern North America and eastern Asia. Magnolias are characteristic of the southeastern U.S. deciduous and semi-evergreen forests, but do not occur naturally in Wisconsin.
14. Cercidiphyllum japonicum — Katsura tree (Cercidiphyllaceae)
Although this plant would appear to have female floral parts composed of several free carpels (apocarpous), anatomical studies have shown that each female flower consists of a single ovary, the inflorescences being so contracted that they resemble a single flower. Though now endemic to China and Japan, Cercidiphyllum is known from Tertiary deposits of the western United States, Greenland, Spitsbergen and elsewhere.
15. Ulmus
americana — American Elm (Ulmaceae)
The genus Ulmus occurs in north temperate regions (Asia, Europe, and North America). The distinctive leaves and fruits of this genus are well-represented in the fossil record and were an important part of the Arcto-Tertiary flora. The architecture of this tree has made it very popular for lining streets and long promenades (see Bascom Hill). Unfortunately, Dutch elm disease, a fungus that attacks and ultimately kills the tree, was introduced into North America during the mid-1900s from eastern Asia. Elms were a very significant element of the eastern deciduous forest prior to the introduction of the disease. Since that time, the majority of American elms have been eliminated by the disease. .
16. Lepidodendron — a giant lycopod (related to extant “clubmosses” of Lycopodiophyta) of the equatorial coal swamps. Two other good websites and websites for this group. [Carboniferous]
17. Calamites — a tree-like horsetail (or “sphenopsid” of the once recognized Equisetophyta, and now in Pteridiophyta or ferns) of the equatorial coal swamps. [Carboniferous]
18. Delnortea (seed fern) — An example of the once diverse and now extinct lineage of woody plants with fern-like leaves but producing seeds like gymnosperms and angiosperms. This fossil genus is restricted to the north-central shales of Texas. [Permian]
19. Sequoia
(redwood) — A fossil Metasequoia (see #10 above) is also on display here. Sequoia once ranged throughout Europe, China, and western North America but is now restricted to California and Oregon.
[Tertiary]
