Asa Gray published two important works that dealt with South American plants. His monumental work of plants of the Wilkes expedition, largely from the South Pacific, enumerated 1,052 species in 557 genera of 83 families of dicots. It included 246 new species, 17 new genera, 48 new combinations, and 26 varieties. The second major work, in collaboration with Joseph Dalton Hooker, discussed disjunctions in general and provided 88 examples of North-South American disjunction. This amphitropical disjunction is briefly presented, with key references cited. Several new examples from the Brassicaceae are presented for the first time, and they demonstrate the three major North-South American amphitropical disjunctions proposed by Peter Raven in 1963.

Recent work on the rise of science in the nineteenth century has encouraged historians to look again at the role of correspondence. Naturalists relied extensively on this form of contact and correspondence was a major element in generating a community of experts who agreed on what comprised valid knowledge. As a leading figure in the development of North American botany, Asa Gray found that letters with botanists and collectors all over the world greatly expanded his areas of influence. Lasting friendships were made and the collections at Harvard were materially advanced. Letters also brought Gray into contact with Charles Darwin, who became a close friend. After publication of Darwin's Origin of Species in 1859, Gray defended Darwinism in the United States and corresponded with him about evolution. This article sets Gray's correspondence with Darwin in the context of the reception of Darwinism in the United States.

“…The news is just this, I am engaged to be married to a lady who I think is every way calculated to make me happy... I have not yet told you her name. It is Jane Loring. Her age I suppose to be 25 or 26, though this of course I do not know directly. I suppose she would not be called handsome, but she has a face beaming with good temper and full of intelligence. She is the perfect admiration of all her friends for her lovely and excellent qualities. She is I believe a truly pious girl, and is indeed a person in whom I have the utmost confidence and trust. She moves in the best, though seldom the most brilliant circles of Boston. Possesses all the usual accomplishments of persons in her station, but is most remarkable for a well-cultivated mind, and for her excellent practical powers.”²

It is well known that Asa Gray's 1859 essay on the floristic connections between Japan and the United States were among the earliest applications of Charles Darwin's theory to be published before Origin of Species. Commonly known as the “Asa Gray disjunction thesis,” Gray's diagnosis of that previously inexplicable pattern not only established his reputation as a philosophical naturalist and incited debate with Louis R. Agassiz, but also left rich issues for botanists to investigate. This paper examines the making of Gray's 1859 essay and its relation to Gray's intellectual development. The first section focuses on how Gray in the 1830s and 1850s accumulated and arranged those cases suggestive of the floristic relationship between North America and East Asia. The second section details the ways in which Gray in the late 1850s integrated those thoughts—suggested to him by Darwin, George Bentham, Joseph D. Hooker, and James D. Dana—in order to explain the cases he had amassed during the past decades. This paper concludes that though it is clear that Gray deliberately intended to deploy Darwin's theory against Agassiz's, his 1859 essay as a whole should not be regarded as or reduced to a mere application of Darwin's theory to botany. Gray did apply Darwin's theory, but applied it in a way Darwin unexpected.

The eight editions of Gray's Manual are overviewed, with special attention being given to the first six, the editions in which Asa Gray was sole author (editions one through five) or co-author (edition six). Changes to the editions are summarized and reviews, positive in the beginning and more critical later with the sixth edition, are discussed. While Gray himself admitted that he failed in his effort to make the Manual a vade mecum he did succeed in providing an excellent identification manual for the region in a single volume. This Manual would be used by almost all students of the flora's region, including those who would criticize later editions when it did not keep up with all of the botanical discoveries that were occurring in the Manual's range.

Asa Gray never expanded his knowledge of floristic bryology to the extent he developed expertise in flowering plant taxonomy. Nevertheless, he became experienced in bryological floristics early in his botanical career, and Gray absorbed new bryological information, both floristic and conceptual, throughout his life from wherever it was generated. He had plans to advance bryology in the United States, including an exsiccata and publishing a volume devoted to cryptogams as part two of the second edition of his Manual, but both never happened. His respect for the bryological talent and energy of William S. Sullivant, whose achievements Gray consistently encouraged and fostered, allowed Sullivant, a non-academic in Columbus, Ohio, to become a highly regarded bryologist of international stature and the designated Father of American Bryology. The growth of bryofloristic knowledge in the United States is traced from the earliest colonial period to later workers, including Dillenius, André Michaux, Palisot de Beauvois, Henry Muhlenberg, Lewis Schweinitz, Lewis Beck, and John Torrey, to Asa Gray, and eventually to William Sullivant. The bryological work and accomplishments of each of them show that all participated in a sophisticated international network of information exchange by letter or other conveyance, thereby building important collections of bryophyte specimens and printed references. For some, this happened during the 1800s when improvements in compound light microscopy led to the resolution of morphology not before revealed with certainty in bryophytes and to conceptual advances in understanding the biology of these plants, which in turn allowed the discovery of the mesoscale structural uniqueness of them and continuing advancements in their systematics in the post-Sullivant era.

At Harvard Asa Gray established academic instruction during the summer and in so doing he opened facilities to an audience that included not only Harvard College students but also teachers and professionals from across North America. The Summer School of Botany established in 1871 spawned the Summer Schools of Natural History, of Chemistry, and of Geology. His summer school and all subsequent offerings included women. This article places Gray's summer school in the context of his efforts to build botany at Harvard but also documents his influence on instruction and curriculum development.

When a young, enthusiastic Asa Gray came to Cambridge in 1842, he brought with him a small but significant collection of herbarium specimens. Some twenty years later, he bequeathed that collection, then numbering some 200,000, to Harvard University. The subsequent growth and direction of “Gray's Herbarium,” and its transformations to the Gray Herbarium and the Harvard University Herbaria, are discussed with respect to five of its Curators and Directors: Sereno Watson, Benjamin L. Robinson, Charles A. Weatherby, Merritt L. Fernald, and Reed C. Rollins.

A second species of the Chilean endemic Ivania, I. juncalensis, is described and illustrated. It is readily distinguished from the generic type I. cremnophila, which is also known only from the type collection, by its pinnatifid and oblong to lanceolate (vs. entire or dentate and cordate to subreniform) basal leaves, smaller flowers (ovate sepals 2.5–3 mm long and spatulate petals 6–7.5 × 2.5–3 mm vs. oblong sepals 5–6 mm long and broadly obovate petals 11–13 × 5–6 mm), and strongly 2-lobed (vs. entire) stigma.

Pinalia shiuyingiana, a new species from Myanmar, is described and illustrated. A related taxon from India, Eria connata Joseph et al., is transferred to Pinalia.

A taxonomic revision of Campylocentrum (Orchidaceae) in Costa Rica is presented. The taxonomic history of the genus and its phylogenetic position are discussed. Characters of vegetative and floral morphology are treated, and their taxonomic significance is discussed. The genus is treated as comprising nine species in the country, and a key to species is provided. Each taxon is described on the basis of Costa Rican material, illustrated in a composite plate, and its distribution within the country is assessed. Distribution maps for all the taxa are given. Overall distribution, derivation of name, notes on species ecology, and diagnostic features are presented for each taxon. The names C. parvulum Schltr. and C. multiflorum Schltr. are neotypified. A new species from Costa Rica, C. generalense, is described and illustrated.

The Dominican Republic moss flora stands out within the Caribbean countries because of the high species richness and number of disjuncts. The flora is comprised of 467 taxa in 207 genera, and 61 families. We report 62 new records and 82 disjuncts for this flora that shows affinity with other Greater Antilles and Central America. Within the context of the Caribbean and in terms of conservation, this flora is important because it represents both the highest reported moss species richness and 82 unique disjuncts within the West Indies.