Chapter 9 



SIMPLE PLANTS WITH CHLOROPHYLL— ALGAE 



Plants Without True Leaves, Stems, or Roots; Not Forming 

 Multicellular Embryos; and Without True Vascular (Conduct- 

 ing) Tissues (Subkingdom Thallophyta) 



GENERAL CHARACTERISTICS OF THALLOPHYTES 



1. Thallophytes include the algae and fungi. The former contain 

 chlorophyll which, in the presence of energy-supplying light, is able to 

 combine carbon dioxide and water to produce carbohydrates through 

 the process of photosynthesis (fo to -sin' the sis) (Or. phos, light; synthe- 

 sis, put together). The fungi lack chlorophyll and are unable to manu- 

 facture their foods but must depend upon outside sources for their 

 nourishment. 



2. Thallophytes are simple plants which lack true leaves, true stems, 

 and true roots. However, certain species may have structures which 

 somewhat resemble them, but they do not possess the two vascular tis- 

 sues (phloem and xylem) of the true organs. 



3. This group of plants is vast and varied, ranging from the unicellu- 

 lar, microscopic types to the large, multicellular forms, some of which 

 are over 200 feet long. Certain species consist of a linear series of cells, 

 while others consist of sheetlike masses of cells; hence the name thallo- 

 phyta (tha -lof'i ta) (Or. thallo, sheetlike or "leaf-shaped"; phyta, 

 plants) . 



4. The sporangia (spor -an' ji a) (Gr. sporos, spore or seed; angios, 

 vessel), which are structures which produce spores, and the gam,etangia 

 (gam e -tan' ji a) (Gr. gametes, gametes or sex cells; angios, vessel), 

 which produce sex cells (gametes), are both usually unicellular. 



5. The zygote (fertilized egg cell) does not produce a multicellular 

 embryo while still within the female sex structure. 



6. Thallophytes do not possess the two vascular tissues called phloem 

 (flo' em) (Gr. phloios, smooth bark) and xylem (zi' lem) (Gr. xylon, 

 wood ) . These two tissues are present in higher plants. 



150 



