. Cryptogamic plants of the USSR. (Flora sporovykh rastenii SSSR). Plants. Melanconiales. added to "pycnidia" the term "; Since the sexual nature of spermatia has been proved, the more appropriate term "spermagonia" should be reestablished. Spermagonia are rather varied in structure (Figure 2). The simplest type is found in genera of Melampsoraceae. Under the cuticle, over the epidermal cells are found the unicellular spermatiophores. These are vertically arranged rather long and thin cells constricted at their tips like beads into small globoid or
. Cryptogamic plants of the USSR. (Flora sporovykh rastenii SSSR). Plants. Melanconiales. added to "pycnidia" the term "; Since the sexual nature of spermatia has been proved, the more appropriate term "spermagonia" should be reestablished. Spermagonia are rather varied in structure (Figure 2). The simplest type is found in genera of Melampsoraceae. Under the cuticle, over the epidermal cells are found the unicellular spermatiophores. These are vertically arranged rather long and thin cells constricted at their tips like beads into small globoid or ovoid spermatia. Spermagonia with a flat layer are also found in many Pucciniaceae,but in Puccinia, Uromyces,and Gymnosporangium the spermagonia are globoid or flask-shaped with the sper- matophores radially arranged over the entire inner surface, with paraphyses projecting from the ostiole (periphyses, ostiolar filaments) (Figure 3). In the genus Gymnosporangivim the spermagonia (hemispherical at the bottom owing to the slight centripetal slope of the spermatiophores) also have ostiolar filaments. In Leucoteliuin, Tranzschelia, and Ochropsora the spermagonia are flat at the bottom with a conical peridium, opening at the apex, with projecting paraphyses. In most genera of Melampsoraceae the spermagonia are flat, or — rarely — somewhat spherical. In species of Cronartium, flat spermagonia without paraphyses develop under the cortex of pine branches. In the majority of genera with flat spermagonia the latter are subcuticular, rarely subepidermal; spherical spermagonia are immersed in the FIGURE 2. Spermagonia: a — subcuticular, in Pucciniastrum; b — under the bark, in Cronartium; c — subepidermal, in Gymnosporangium. (After Arthur, 1929.) 42 The spermagonia secrete a sweet, fragrant, thick fluid sought by insects which transport the spermatia and are thus instrumental in the reproductive process. Spermagonia are always produced on the mycelium arising from
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectplants
