UKTICA. 



[ 797 ] 



USTILAGO. 



Two species j freshwater. (Cl. & Lachm. 

 Inf. 314; Kent, Inf. 504.) 



URTI'CA, L. A genus to which the 

 .-tinging-nettle belongs (see STINGS). 



US'NEA, Ach. A genus of Bamalodei 

 (Lichenaceous Lichens), with a somewhat 

 crustaceous branched thallus, bearing pel- 

 tate apothecia, which often have a ciliated 

 margin. U. barbata is common on park- 

 pales and old trees, U.florida vo&fiKeata in 

 similar situations, mostly in mountainous 

 regions. The pendulous fibrillous thallus 

 and ciliated apothecia of U. barbata are 

 very characteristic. 



BIBL. Hook. Br. FL ii. pt. 1. 230; Leigh- 

 ton, Lich. FL 75. 



USTILAGIN EM. A family of Hypo- 

 dermous Fungi related to the Urediuei, 

 generally distinguished by their growing in 

 the interior of the organs (especially the 

 ovaries and anthers) of Flowering Plants, 

 causing deformity, absorption of the internal 

 tissue, and its replacement by a pulverulent 

 substance consisting of the" spores of the 

 Fungi. In the earlier stages, the infected 

 organ exhibits either a grumous mass, or 

 an interwoven filamentous mycelium, from 

 which acrogenous spores arise ; finally the 

 mycelium disappears, and a dark-coloured 

 (often foetid) powder remains, composed 

 entirely of the spores, which are simple, or 



Fig. 781. Fig. 782. 



Fig. 783. 



Fig. 784. 



Fig. 785. 



Thecaphora deformans. 



Compound spores, entire and broken up. 



Magnified 460 diameters. 



more rarely compound (figs. 784, 785), i. e. 

 several coherent within a common coat, at 

 length free (figs. 781-783), smooth or 

 unequally echinate or reticulated. 



BIBL. Berk. Br. Fl, (art. Uredo) ; Tulasne, 

 Ann. So. Nat. 3. vii. 5, ii. 157 ; De Bary, 

 Brandpilze; Bauer and Banks, Cttrtis's 



Pract. Obs. on Br. Grasses, 1805; Unger, 

 Exanthem. Plant. ; Fischer v. Waldlieim, 



Ustilaf/mt'i. 



USTILA'GO, Fries.- 

 laginei (Hypodermous 



Fig. 786. 



-A genus of Usti- 

 Fungi), forming 



Fig. 787. 



Fig. 786. Ustilago Carbo, on oats. Nat. size. 

 Fig. 787. Ustilago Carbo, on barley. Nat. size. 



smuts, infesting the ears of corn and other 

 grasses, the ovaries and anthers of other 

 Flowering Plants, and in some cases the 

 leaves and stems of plants. The interior of 

 the organ infested by them presents at 

 first a grumous-mucous whitish mass, which 

 grows at the expense of the tissue and juice 

 of the infested organ, and is finally con- 

 verted into a pulverulent mass of simple 

 spores, mostly of deep colour, and with a 

 smooth, spiny or reticulated surface. 



The species growing upon leaves and 

 stems occur on grasses, e. g. U. longissima 

 ( Uredo longissima, Sow.), U. hypodytes ( Ur. 

 hypodytes}, and U. grandis (or typhoides) ; 

 they form linear patches, ultimately con- 

 taining smooth black spores. 



The greater number, however, occur in 

 the parts of flowers, especially of grasses 

 Ust. Carbo (Uredo segetum, Pers.), form- 

 ing the blight called smut of corn, com- 

 monly infesting wheat, oats (fig. 786), barley 

 (fig. 787), and other grasses, filling the ears 

 with a black powder of smooth spores, 

 about 1-5000" in diameter in corn, some- 

 times about twice as large in the varieties 

 attacking species of Bromus. The smut of 



