| Systematics of Pappobolus (Asteraceae-Heliantheae) | 1992/01/01 | English | 16 |
| Monograph of Ruprechtia (Polygonaceae) | 2004/01/01 | English | 16 |
| Monograph of Aciotis (Melastomataceae) | 2002/01/01 | English | 16 |
| Biogeography and Systematics of Poitea (Leguminosae): Inferences from Morphological and Molecular Data | 1993/01/01 | English | 16 |
| Systematics of Clermontia (Campanulaceae-Lobelioideae) | 1991/01/01 | English | 15 |
| Revision of Geranium Subgenus Erodioidea (Geraniaceae) | 1996/01/01 | English | 15 |
| Systematics of Coursetia (Leguminosae-Papilionoideae) | 1988/01/01 | English | 15 |
| Systematics of Oropogon (Alectoriaceae) in the New World | 1989/01/01 | English | 15 |
| Systematics of Tetramerium (Acanthaceae) | 1986/01/01 | English | 14 |
| Systematics of Epilobium (Onagraceae) in China | 1992/01/01 | English | 14 |
| Systematics of Simsia (Compositae-Heliantheae) | 1990/01/01 | English | 13 |
| Systematics of Oenothera Section Oenothera Subsection Raimannia and Subsection Nutantigemma (Onagraceae) | 1988/01/01 | English | 13 |
| Systematics of Columnea Section Pentadenia and Section Stygnanthe (Gesneriaceae) | 1994/01/01 | English | 13 |
| Monograph of the Eremolepidaceae | 1988/01/01 | English | 13 |
| Systematics of Frankenia (Frankeniaceae) in North and South America | 1987/01/01 | English | 12 |
| A Monograph of Leochilus (Orchidaceae) | 1986/01/01 | English | 11 |
| Taxonomy of Complaya, Elaphandra, Iogeton, Jefea, Wamalchitamia, Wedelia, Zexmenia, and Zyzyxia (Compositae-Heliantheae-Ecliptinae) | 1991/01/01 | English | 11 |
| Systematics of Antirrhinum (Scrophulariaceae) in the New World | 1988/01/01 | English | 11 |
| Revision of Gasteranthus (Gesneriaceae) | 2000/01/01 | English | 10 |
| Revision of Hieracium (Asteraceae) in Mexico and Central America | 1990/01/01 | English | 9 |
| Systematics of the Annual Species of Muhlenbergia (Poaceae-Eragrostideae) | 1991/01/01 | English | 9 |
| Monograph of Orbea and Ballyanthus (Apocynaceae-Asclepiadoideae-Ceropegieae) | 2002/01/01 | English | 8 |
| The Taxonomy of Saxifraga (Saxifragaceae) Section Boraphila Subsection Integrifoliae in Western North America | 1984/01/01 | English | 7 |
| Revision of Cuphea Section Diploptychia (Lythraceae) | 1998/01/01 | English | 7 |
| Systematics of Cobaea (Polemoniaceae) | 1999/01/01 | English | 7 |
| Systematics and Evolution of Cordylanthus (Scrophulariaceae-Pedicularieae) (Including the Taxonomy of Subgenus Cordylanthus) | 1986/01/01 | English | 6 |
| Systematics of Cryosophila (Palmae) | 1995/01/01 | English | 5 |
| Taxonomy of Lygodesmia (Asteraceae) | 1980/01/01 | English | 3 |
| Systematics of Tuberous Lomatiums (Umbelliferae) | 1984/01/01 | English | 2 |
| Revision of Philodendron Subgenus Pteromischum (Araceae) for Pacific and Caribbean Tropical America | 1996/01/01 | English | |