Gymnosperms Native species found on campus.. Dade County Slash Pine Pinus elliottii var. densa Phylum Coniferophyta This extreme southern variety of the.

Presentation on theme: "Gymnosperms Native species found on campus.. Dade County Slash Pine Pinus elliottii var. densa Phylum Coniferophyta This extreme southern variety of the."— Presentation transcript:

1 Gymnosperms Native species found on campus.

2 Dade County Slash Pine Pinus elliottii var. densa Phylum Coniferophyta This extreme southern variety of the slash pine grows in a few remaining stands on the rock ridge of South Florida. Most of the coastal areas of south Florida, on the limestone ridge, were covered with a pine forest, called the pine rocklands. Little of this forest remains, having been replaced by agriculture and then commercial development. Its wood is very resinous, extremely hard when dry, and very resistant to termite attack. It was used in the construction of homes and boats well into the last century. Dade County slash pine grows in the Ecosystem Preserve and the parking lot just to the east. A couple of trees also grow in the small conifer collection NE of the north parking lot. The fragile male cones and small purplish female cones develop in January and February. In a forest, the air is yellow with the wind-carried pollen. After fertilization, the female cone scales swell and close. Then the cones develop for the entire year, and open to release the winged seeds prior to the rainy season (May) the next year. The trees always have female cones in some stage of development, but the male cones fall off the tree soon after they shed their pollen. The Dade County Pine is a member of the pine family (Pinaceae) along with all pines and the firs, such as the Frazer’s fir from the Appalachian Mountains on sale before Christmas.

3 Bald Cypress Taxodium distichum Phylum Coniferophyta This is a conifer in another family, the Taxodiaceae. Its female cones are much smaller and the individual scales are rounded to produce a round cone. It is a swamp tree, growing in stands throughout the southeast. It was once common in a strip of swamp forest down the southeast coast of Florida, and more common along the west coast, as in the Big Cypress National Preserve. Bald Cypress trees were planted on pond margins at FIU soon after it opened. We now have some bald cypress “domelets”, with cypress knees (the pneumatophores that assist in oxygen uptake to the roots) and Everglades wading birds sitting on branches. The bald cypress is unusual among conifers in that it loses its short needle foliage during the winter months. Few of the original cypress domes remain. The majority of these swamp forests were logged before and during the Second World War, partly for the construction of PT boats.

4 Zamia Life Cycle Phylum Cycadophyta These gymnosperms are no longer widely distributed, only found in mostly dry tropical regions, but they were once dominant plants. These were the primary food of the large herbivorous dinosaurs. Most cycads are extremely tough, thorny, and often very toxic. Fairchild Tropical Garden, and the adjacent Montgomery Botanical Center, have the largest cycad collection in the world. Cycads have life cycles similar to the conifers, but certain details (as the flagellate male gametes) are different. Cycad plants are female (producing long-lived female cones) or male (producing ephemeral male cones). We illustrate the cycad life cycle with the example of the coontie, Zamia pumila.

5 Coontie Zamia pumila Phylum Cycadophyta The coontie is the only cycad native to the United States, growing in South Florida Pinelands. Its rhizomes are full of starch, which was the source of the first manufacturing industry in south Florida. The "trunks" were ground up to release the starch. The starch was then washed to remove the toxic cycasin, and the product dried and ground. Florida “arrowroot” was then shipped up the east coast for cooking and stiffening the collars of Victorian shirts. The coontie is a small plant, less than half a meter high. It grows on campus in the Ecosystem Preserve, the Campus Security Compound, and by the Conservatory. Recently, the remarkable discovery was made that the coontie is pollinated by beetles, which feed on both the male and female cones.