Simple Plants Without Chlorophyll — Fungi 173 



each having one to two flagella. The myxamoeba locomotes by flagellar 

 action or by amoeboid pseudopodia. Two myxamoebae fuse in a form 

 of sexual reproduction to form a zygote (zi'gote) (Gr. zygotos, joined). 

 Several zygotes may fuse to form a new plasmodium in which the nuclei 

 have not fused. Some common slime molds include Stemonitis (Fig. 35), 

 Lycogala (Fig. 35), Badhamia, Physarum, etc. 



TRUE (HIGHER) FUNGI (PHYLUM EUMYCOPHYTA) 



A. Class Phycomycetes (fi ko my -ce' tez) (Gr. phykos, seaweed; mykes, 

 fungus) 



1. Black Bread Mold {Rhizopus nigricans) (ri'zopus; ni' gri kans) 

 (Gr. rhiza, root; pons, foot) (L. nigricans, black). — This mold is typical 

 of the black molds which are common saprophytes on moist, organic ma- 

 terials such as bread, fruits, potatoes, animal dung, etc. A few species 

 may parasitize man and other animals. Certain species parasitize squash, 

 cowpeas, cotton, and other plants. Other species are used commercially 

 in the production of alcohol, acids, enzymes, etc. They are called black 

 molds because of their dark-colored spores. 



The irregular, whitish or grayish, mass of threadlike hyphae (hi' fe) 

 (Gr. hyphe, web) comprise the weblike mycelium (mi-se'lium) (Gr. 

 myxos, fungus) (Fig. 36). The young hyphae are branched and with- 

 out cross walls (nonseptate) and contain numerous nuclei, while cross 

 walls (septa) may be present in older hyphae, especially when reproduc- 

 ing sexually. Rootlike hyphae known as rhizoids (ri'zoid) (Gr. rhiza^ 

 root; eidos, form) absorb nourishment from the substratum and serve 

 as anchors. Other hyphae grow over the surface and are called stolons 

 (sto' Ions) (L. stolo, shoot), from which arise the spore-forming hyphae 

 known as sporangiophores (spor -an' jio for) (Gr. sporos, spore; ang- 

 geion, vessel; pherein, to bear). Each- sporangiophore bears a globular 

 spore case (sporangium) at its tip which becomes darker as it matures. 

 The air-borne, asexual, nonmotile spores germinate to form hyphae. 



Sexual reproduction occurs by the formation of small projections be- 

 tween two adjacent hyphae. The projections fuse and each forms a sex 

 cell (gamete). The two gametes fuse in the fertilization process known 

 as conjugation, thus producing a zygote (zygospore). The latter devel- 

 ops a new hypha. The two types of hyphae necessary for the sexual 

 process are called "plus" and "minus" hyphae or strains. 



2. Water Mold (Saprolegnia) (sap ro -leg' ni a) (Gr. sapros, rotten; 

 legnon, edge). — The fungi of this group are primarily saprophytes in 



