HUNTIA A Journal of botanical History VolUme 12 NUmber 1 2005 Hunt Institute for botanical Documentation Carnegie mellon University Pittsburgh The Hunt Institute for botanical Documentation, a research division of Carnegie mellon University, specializes in the history of botany and all aspects of plant science and serves the international scientific community through research and documentation. To this end, the Institute acquires and maintains authoritative collections of books, plant images, manuscripts, portraits and data files, and provides publications and other modes of information service. The Institute meets the reference needs of botanists, biologists, historians, conservationists, librarians, bibliographers and the public at large, especially those concerned with any aspect of the North American flora. Huntia publishes articles on all aspects of the history of botany, including exploration, art, literature, biography, iconography, and bibliography. 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Hunt Institute for botanical Documentation Carnegie mellon University 5000 Forbes Avenue Pittsburgh, PA 15213-3890 Telephone: 412-268-2434 email: [email protected] Web site: http://huntbot.andrew.cmu.edu/ HIbD/Publications/HI-Pubs/Pub-Huntia.shtml editor Scarlett T. Townsend book reviews and Announcements editor Charlotte A. Tancin Associate editors Gavin D. r. bridson T. D. Jacobsen Angela l. Todd Frederick H. Utech James J. White Designer Lugene b. bruno Photographer Frank A. reynolds Printed and bound by Hoechstetter Printing, Pittsburgh, PA © 2005 Hunt Institute for botanical Documentation All rights reserved ISSN 0073-4071 Huntia 12(1) 2005 the inside story: a commentary on the study of lichen structure in the 18th and 19th centuries M. E. Mitchell Abstract Observations concerning the vegetative anatomy of are known (Sipman and aptroot 2001), lichens were first reported in 1784; these did little more lichens display a wide range of variation;1 for than record the presence of green cells, and it was not descriptive purposes, therefore, three principal until early in the 19th century that lichens were also shown to contain colorless filaments. Several studies growth forms are recognized: crustose, foliose undertaken in the first half of the 1820s established the and fruticose (Figs. 1–3). basic features of lichen anatomy, but from then until For most of the period under consideration mid-century the subject attracted scant attention; when here, lichens were believed to be autonomous work did resume, this involved macrolichen material in particular. Considerable histological detail was reported, plants, related to, but distinct from algae and and the cortical structures peculiar to lichens were fungi. that belief was not contested until thoroughly investigated. Despite a growing awareness of the late 1860s when, as a result of anatomical an affinity between the green cells of lichens and certain investigation, the hypothesis was advanced algae, it was not until the latter half of the 1860s that the thallus was understood to be a structure elaborated that lichens are fungi living parasitically on by fungal hyphae in combination with algae or blue- algae.2 this insight created serious problems green algae (as cyanoprokaryotes were then known). for those botanists who specialized in lichen Microlichen anatomy, which hitherto had received taxonomy — it not alone undermined the comparatively little attention, was well documented during the last three decades of the century. Over the independence of their subject but also seemed years, terminology had kept pace with developments, to call in question the validity of every binomial and much the greater part of that currently used in the that had been applied to lichens. if these really area of lichen structure was in place by the end of the were dual organisms, each component would 19th century. have, or would have to receive, a binomial, and lichen names themselves would, it was feared, Introduction become redundant. no such jettisoning had, Lichens are fungi growing in symbiotic however, to be undertaken because, unlike association with photosynthetic microorganisms. the photosynthetic components, which also this association generally exerts a profound occur in the free-living state and have each morphogenetic effect on the fungal component, a binomial, lichen fungi are not found other which, in consequence, forms a macroscopic than in symbiotic association: lichen names structure that houses its nutritive partner. Since therefore apply, strictly speaking, to the fungal 3 the morphology of this structure is determined component and not to the dual organism. by the particular species that constitute each association, and since close to 14,000 such Internal investigations the earliest anatomical study of lichens Department of Botany, national university of was undertaken by Pier Micheli (1679–1737), ireland, Galway, ireland. 13 14 Huntia 12(1) 2005 Figure 1. Rhizocarpon concentricum (Davies) Beltr., Figure 2. Lobaria pulmonaria (L.) Hoffm., a foliose a crustose lichen. (From Hoffmann 1790–1801, 3: lichen. (From Hoffmann 1790–1801, 1: pl. 1, fig. 2.) pl. 50, fig. 2.) superintendent of the Botanical Garden at cells — Hedwig states (1784, p. 122, n. i) that, Florence. He provided the first directions in this figure, the “darker islands represent (1729, p. 74) for preparing sections of lichen particles of clustered, green parenchyma that reproductive bodies, and illustrated the often extend as far as the cuticle.”5 procedure clearly (1729, pl. 52, fig. G), but By the end of the 18th century, the study did not apply his technique to the vegetative of lichens had begun to emerge as a distinct part of a lichen. the initiative in that regard discipline, a development largely attributable was taken, though not until more than 40 to the work of Erik acharius (1757–1819). years after Micheli’s death, by Johann Hedwig He had been in medical practice for nine (1730–1799). He was in medical practice at years at Vadstena, southern Sweden, when Chemnitz when the imperial academy of his first major publication, Lichenographiae St. Petersburg announced in 1779 (Lütjeharms Suecicae Prodromus (1798), appeared. that 1936, p. 107) that a prize was to be awarded work considerably facilitated identification by in 1783 for a study of reproduction in providing descriptions of about 400 species; cryptogamic plants; Hedwig submitted what acharius accommodated all of these in the proved to be the winning entry, which was Linnaean genus Lichen, but five years later he published by the academy under the title replaced that genus with 25 new genera based Theoria Generationis et Fructificationis Plantarum on fruit–body morphology (acharius 1803). Cryptogamicarum (1784). the 37 plates that He also helped underpin the independent status accompany Hedwig’s report were described by of the subject by coining a range of specialist Morton (1981, p. 322) as providing “the most terms, some of which soon found wider accurate and beautiful figures of cryptogams application: “apothecium,” “perithecium,” yet produced by anyone,”4 but the illustrations “soredium” and “thallus” are among his of lichens do not merit such commendation. introductions (1803, pp. vii, ix, xviii, xxi).6 at One of these (see Fig. 4) is, however, of this stage, however, acharius did not report particular relevance to the present survey: in any microscopical observations. addition to being the first diagram of a section the first account of lichen structure to through the vegetative body of a lichen, it is appear in the 19th century was published by the first attempt to depict the photosynthetic Kurt Sprengel (1766–1833), professor of botany Mitchell: The inside story 15 Figure 4. Vertical section through a lobe of Anaptychia ciliaris (L.) Körber; the drawing shows a reproductive structure (center) in addition to groups of algal cells. (From Hedwig 1784, pl. 31, fig. 177.) Sprengel’s conclusions were amplified by Heinrich Link (1767–1851), professor of botany at the university of Rostock. He described the lichen cortex (1807, p. 25) as composed of “vesicular tissue analogous to parenchyma,”8 and the interior of the thallus as containing “filamentous tissue” (“fasrige Gewebe”), the individual filaments of which he found to be septate (p. 21). From a study Figure 3. Usnea sp., a fruticose lichen. (From involving Pseudocyphellaria aurata (ach.) Vainio Hoffmann 1790–1801, 3: pl. 72, fig. 1.) (as Sticta aurata (ach.) ach.), Link was able to establish that “granules” (“Körnern”) at the university of Halle. in a brief anatomical corresponding to those present in soredia survey, Sprengel (1802–1804, 3:323–326) occur within the thallus; his illustration of the described lichens as “compact or gelatinous latter category (1807,