(rather than herbaceous) in that the sylem often displays secondary growth (widening of the
trunk). They generelly have only tracheids for water conduction and lock vessel elements, which
are characteristic of angiospems 1. Division: Cycadophyta Although there is only about 100
extant species of cycads, this phylum was significant during the Thassic period (248 million
years ago). They are tropical and subtropical plants with trunk-fike stems and compound leaves
and are popular as omamentals. These plants are dioecious in that seed cones and pollen cones
are on two separate plants. Because of their palm-like structure, they are sometimes incorrectly
descrbed as paim treces. However, lke other gymnosperms they produce oones and lack flowers.
Examples of cycads include False king sago and Florida coonte (Zartia pumita). Zamia pumila is
the only cycad native to the United States. ACTIVITY 1: Examine the live plant andior cones if
available. (Use the atlas if necessary.) II. Division: Gnetophyta There are about 70 species of
gnetophytes, which include tropical shrubs and vines. Some species (e.g. Ephedra, Wetwitschia)
are found in deserts and other dry regions. Gnetophytes are believed to be the most closely
related to flowering plants. They possess more efficient water-conducting cells (vessel elements)
in their xylem, which is typical of angiosperms, but absent in the other gymnosperms. The leaves
of gnetophytes are also similar to that of angiosperms and some species have flower-like
structures. Gnetopytes are classified as gymnosperms primarily because their reproductive
structures are cones (strobili)..
(rather than herbaceous) in that the sylem often displays secondary gr.pdf
1. (rather than herbaceous) in that the sylem often displays secondary growth (widening of the
trunk). They generelly have only tracheids for water conduction and lock vessel elements, which
are characteristic of angiospems 1. Division: Cycadophyta Although there is only about 100
extant species of cycads, this phylum was significant during the Thassic period (248 million
years ago). They are tropical and subtropical plants with trunk-fike stems and compound leaves
and are popular as omamentals. These plants are dioecious in that seed cones and pollen cones
are on two separate plants. Because of their palm-like structure, they are sometimes incorrectly
descrbed as paim treces. However, lke other gymnosperms they produce oones and lack flowers.
Examples of cycads include False king sago and Florida coonte (Zartia pumita). Zamia pumila is
the only cycad native to the United States. ACTIVITY 1: Examine the live plant andior cones if
available. (Use the atlas if necessary.) II. Division: Gnetophyta There are about 70 species of
gnetophytes, which include tropical shrubs and vines. Some species (e.g. Ephedra, Wetwitschia)
are found in deserts and other dry regions. Gnetophytes are believed to be the most closely
related to flowering plants. They possess more efficient water-conducting cells (vessel elements)
in their xylem, which is typical of angiosperms, but absent in the other gymnosperms. The leaves
of gnetophytes are also similar to that of angiosperms and some species have flower-like
structures. Gnetopytes are classified as gymnosperms primarily because their reproductive
structures are cones (strobili).
