404 DESCEIPTION OF PLATES. 



PLATE XXV. 



Urtica Breweri, Watson. — Natural size. Fig. 1. Staminate flower. Fig. 2. Pistillate flower, 

 Fig. 3. Achenium, enclosed by the large inner sepals. Fig. 4. Calyx, opened, showing mature ache- 

 nium. All enlarged about 10 diameters. 



PLATE XXVI. 



SrsYRTNCHiUM Arizonicum, Rothr. — Natural size. Fig. 1. Stamen, seen from outside. Fig. 2. 

 Stamen, seen from inside. Fig. 3. Styles and stigmas. Fig. 4. Flower, divested of perianth. Fig. 5. 

 Capsule. All enlarged. 



PLATE XXVH. 



Trisetum Wolfii, Vasey. — Fig. 1. Plant, natural size. Fig. 2. Spikelet, enlarged 5 times. Fig. 

 3. Floret, showing the palets and linear seed. 



Trisetum alpestre, Beauv. — Fig. 4. Natural size. Fig. 5. Spikelet, magnified 6 diameters. 

 Fig. 6. Spikelet, with glumes removed. The last should have shown a little pubescence on the stem.of 

 the upper floret. 



Velfa minima, Vasey. — Fig. 7. Natural size. Fig. 8. Flower, enlarged 15 times. Fig. 9. Section 

 of stem, greatly enlarged. 



PLATE XXVIII. 



Poa Wheeleri, Vasey. — Fig. 1. Plant, natural size. Fig. 2. Spikelet, magnified 5 times. Fig. 

 3. Upper floret, with rudiment, enlarged 9 times. 



PLATE XXIX. 



Festuca Thurberi, Vasey.— Natural size. Fig. 1. Spikelet, enlarged 5 times. Fig. 2. Upper 

 glume. Fig. 3. Lower glume. Fig. 4. Upper palet. Fig. 5. Lower palet. 



PLATE XXX. 



NothoLjEna Hookeri.— Ordinary size. Fig. 1. Scale of the rootstock. Fig. 2. Scale from the 

 base of the stalk. Fig. 3. Segment of one of the pinnae, showing the sporangia and the slightly recurved 

 margin. The details are enlarged about 6 diameters. 



