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EXPLANATION OF THE PLATES. 
Plate XVI. LAYJA PENTACH A5TA. — Page 108. 
A FLOWERING BRANCH OF THE NATURAL SIZE. 
Fig. 1. 
2 . 
3. 
4. 
6 . 
6 . 
7. 
8 . 
9. 
10 . 
Vertical section of part of a liead of flowers ; enlarged. 
A ray flower, with its embracing involucral scale. 
A marginal palea of the receptacle. 
A disR flower. 
A stamen of the same ; magnified. 
Style of a ray flower ; magnified. 
Style of a disk flower ; equally magnified. 
Involucre and receptacle ; enlarged. 
Aehenium of a ray flower without its scale. 
Achenium of a disk flower, with its pappus ; the details variously magnified. 
Plate XVII A. CALAIS BIGELOVII.— Page 113. 
A PLANT OF THE NATURAL SIZE. 
Fig. 1. A separate flower ; magnified. 
2. Divisions of the style, showing the stigmatic lines ; highly magnified. 
3. An exterior achenium, and 
4. An interior achenium ; both moderately enlarged. 
5. A separate palea of the pappus. 
Plate XVII, B. CALAIS TENELLA.— Page 114. 
Fig. C. A separate flower ; magnified. 
7. Divisions of the style ; highly magnified. 
8. An achenium, destitute of pappus. 
9. Another achenium crowned with two awned palese. 
10. The receptacle. The last three figures equally magnified. 
Plate XVIII. CALAIS CYCLOCAltPHA.— Page 113. 
Fig. 1. A flower ; magnified. 
2. A stamen ; more highly magnified. 
3. The style ; equally magnified. 
4. An achenium crowned with its pappus ; magnified. 
5. A single palea ; equally magnified. 
6. Keceptacle ; enlarged. 
Plate XIX. ERIOGONUM LACHNOGYNUM.— Page 132. 
an entire plant of the natural size. 
Fig. 1. An involucre, from which several flowers protrude ; magnified. 
2. Perianth laid open ; more magnified. 
3. A pedicel, with a pair of bracteoles at its base ; equally magnified. 
3 a. A third and broader bracteole, inserted exterior to the others ; equally magnified. 
4. The pistil; more magnified. 
5. A ripe achenium ; considerably enlarged. 
6. Embryo, from the same. 
Plate XX. OBIONE HYMENELYTRA.— Page 129. 
Fig. 1. A branch, with male flowers, of the natural size. 
2. A branch from a female plant, with fruit, of the natural size. 
3. A male flower ; magnified. 
4. A female flower ; also magnified. 
5. The same, with one bract removed to show the pistil; more enlarged. 
6. Embryo ; considerably magnified. 
