Rolf Rutishauser

• Prof.em. PhD
• Professor at University of Zurich

Podostemaceae are a clade of aquatic flowering plants that form important components of tropical river ecosystems. Species in the family exhibit highly derived growth forms and high vegetative phenotypic plasticity, both of which contribute to taxonomic confusion. The backbone phylogeny of the family remains poorly resolved, many species remain to...

Background and aims – Podostemaceae is a family of strictly aquatic plants found in rapids and waterfalls. Despite a recent treatment in the Flore du Gabon, the family remained poorly known, with no major studies including Gabonese collections, and almost no targeted inventories since 1966. We present the first large-scale inventory of this family...

Morphological concepts are used in plant evo-devo (evolutionary developmental biology) and other disciplines of plant biology, and therefore plant morphology is relevant to all of these disciplines. Many plant biologists still rely on classical morphology, according to which there are only three mutually exclusive organ categories in vascular plant...

Multicellular plants such as angiosperms are used to having identity crises on various levels, from cells to meristems and organs and even beyond. Identity crises, however, are not the problem of the plants, but of our inadequate thinking and concepts.

The genus Utricularia includes around 250 species of carnivorous plants, commonly known as bladderworts. The generic name Utricularia was coined by Carolus Linnaeus in reference to the carnivorous organs (Utriculus in Latin) present in all species of the genus. Since the formal proposition by Linnaeus, many species of Utricularia were described, bu...

Plants and animals are both important for studies in evolutionary developmental biology (EvoDevo). Plant morphology as a valuable discipline of EvoDevo is set for a paradigm shift. Process thinking and the continuum approach in plant morphology allow us to perceive and interpret growing plants as combinations of developmental processes rather than...

Wie bei andern Biowissenschaften gibt es innerhalb der Pflanzenmorphologie hauptsächlich zwei Denkschulen. Holistisch veranlagte Vertreter betonen den heuristischen Wert komplementärer Perspektiven, von Kontinuum, Fuzziness und Prozessdenken (im Sinne von «sowohl-als-auch»). Mehr reduktionistisch agierende Pflanzenmorphologen vertrauen auf eindeuti...

Phyllotaxis, i.e., the arrangement of leaves around the stem and leaf-like organs inside flowers is regular in most vascular plants. Thus, developmental models usually explain regular phyllotactic patterns such as Fibonacci spirals and decussate/whorled patterns that obey Hofmeister’s rule: primordia form as far away as possible from previously ini...

Background: Various groups of flowering plants reveal profound ('saltational') changes of their bauplans (architectural rules) as compared with related taxa. These plants are known as morphological misfits that appear as rather large morphological deviations from the norm. Some of them emerged as morphological key innovations (perhaps 'hopeful mon...

A new species is added to the monotypic African genus Djinga. Djinga cheekii Ghogue, Huber & Rutish. (Podostemaceae) is described as a new species from Cameroon (Littoral Province) and its morphological affinities and conservation status are assessed. The main distinguishing characters are: stamens 2 (not 1 as in D. felicis), flower buds inside spa...

The river‐weed family Podostemaceae (c. 300 species in c. 54 genera) shows a number of morphological innovations to be adapted to its unusual aquatic habitat, and its unique or rare bauplan features have been reflected in the traditional (i.e. non‐molecular) classification recognizing numerous monotypic or oligospecific genera. The infrasubfamilial...

Both phyllodes and so-called stipules develop on a whorl platform that surrounds the shoot apex. Phyllodes usually are initiated as radial primordia. During their development, although they become acrovergent and show a slight differentiation gradient from the abaxial towards the adaxial side, they retain a circular outline in transection until mat...

In this developmental investigation of Utricularia foliosa and U. australis by means of scanning electron microscopy we demonstrate the relativity of morphological facts and descriptions. We provide several descriptions in terms of the structural categories "stem" and '"leaf." These contrasting, if not contradictory, descriptions are complementary...

The pinnately compound leaves of Chisocheton tenuis, a small tree from Papua New Guinea, exhibit indeterminate growth and periodically produce new pinnae from a leaf tip bud. Inflorescences and vegetative shoots arise from epiphyllous buds on the adaxial surface of the rachis between the pinna pairs. Axillary buds occur on the stem but are always v...

The clusioid clade includes five families (i.e., Bonnetiaceae, Calophyllaceae, Clusiaceae s.s., Hypericaceae, and Podostemaceae) represented by 94 genera and ≈1900 species. Species in this clade form a conspicuous element of tropical forests worldwide and are important in horticulture, timber production, and pharmacology. We conducted a taxon-rich...

The whorls of Acacia longipedunculata consist of 15–27 terete phyllodes and as many setaceous stipules. Their four most surprising features are as follows. (i) Only five to eight traces leave the stele within a whorl node; branches of these supply all appendages (phyllodes, stipules), (ii) The development of a new whorl starts with a polygonal bulg...

Mulga (Acacia aneura F. Muell. ex Benth. and its close relatives) is a very diverse, taxonomically complex and important group of species that is wide-spread and common in many parts of the inland, arid Australia. This preliminary morpho-anatomical examination of Mulga pods is based on selection of taxa that represent the range of carpological and...

The Podostemaceae are highly enigmatic plants which are restricted to submerged river-rock habitats. The availability of new material of nine taxa from continental Africa prompted this new study. Five species belonging to the genera Dicraeanthus, Leiothylax, Letestuella, Macropodiella, and Stonesia and another four species of the large genera Inver...

Djinga is a monotypic genus restricted to the Cameroon Ridge (‘Dorsale Camerounaise’) of NW Cameroon. Besides the type locality Mount Djinga (Adamawa Province, near Tignère), it also grows in waterfalls near Mount Oku (NW Province). This paper describes the structure and development of Djinga felicis using scanning electron microscopy and microtome...

The traditional circumscription of the genus Stonesia G. Taylor (Podostemaceae, Podostemoideae) includes three species restricted to western tropical Africa. Here, a new species, S. ghoguei E. Pfeifer & Rutishauser, is described, which represents the first Cameroonian member of the genus. There are another three Stonesia species restricted to weste...

Dalzellia gracilis, an enigmatic species of Podostemaceae, is characterized by the subcylindrical creeping roots and dorsiventral ribbonlike shoots borne on the roots. To reveal the phylogenetic relationships of D. gracilis, molecular phylogenetic and morphological analyses were performed. A matK tree indicates that it is most likely sister to a cl...

Charles Darwin wird oft nur mit der Evolutionstheorie in Verbindung gebracht. Die vorliegende Arbeit betont Darwins Verdienste bei der Erforschung von Pflanzen. Seine Beobachtungsgabe verbunden mit experimentellem Geschick verhalfen Darwin zu botanischen Entdeckungen, für die wir ihn am 200. Geburtstag ebenso ehren sollten wie für seine mit natürli...

This paper discusses problems with labelling plant structures in the context of attempts to create a unified Plant Structure Special attention is given to structures with mixed, or doubtful identities that are difficult or even impossible to with a single term. In various vascular plants (and some groups of animals) the structural categories for th...

This paper discusses problems with labelling plant structures in the context of attempts to create a unified Plant Structure Ontology. Special attention is given to structures with mixed, or doubtful identities that are difficult or even impossible to label with a single term. In various vascular plants (and some groups of animals) the structural c...

Apinagia (c. 50 spp.) is the largest genus of American Podostemaceae. Apinagia multibranchiata (Matth.) Royen is a haptophyte endemic to the Venezuelan Guyanas. It fits well with the Podostemoideae bauplan known from other New World genera, such as Marathrum and Mourera. Shoots arise in pairs from filamentous creeping adhesive roots. During the rai...

Evolutionary developmental biology, or 'evo-devo', is the study of the relationship between evolution and development. Dealing specifically with the generative mechanisms of organismal form, evo-devo goes straight to the core of the developmental origin of variation, the raw material on which natural selection (and random drift) can work. Evolving...

A new species of Podostemaceae subfamily Podostemoideae, Ledermanniella ntemensis, is from southwestern Cameroon. It is characterized by the sparse scales on the shoot branches and the three stigmas.

Macroscopic nature is never really anomalous. Abnormalities, like other exceptional cases, at least show incontestably, what the plants can do. Arber 1950: 6 However, regardless of how much faith one has in anatomical definitions, they should not be taken as more than a means of communication prior to subsequent genetic analysis. Scheres et al. 199...

Thelethylax (2 species) is one of three podostemoid genera, which are endemic to Madagascar. This paper deals with the structure and development of T. minutiflora. Characters typical for this species include: green ribbon-like roots have exogenous finger-like holdfasts; root tips are covered with prominent dorsiventral caps; shoots arise mainly fro...

The leaf rosettes of the carnivorous Pinguicula moranensis follow a spiral phyllotaxis approaching a Fibonacci pattern while the stalked flowers arise from extra-axillary sites between the leaves. The organization of this rosette has been discussed by various authors, with various results. The aim of the present study was to clarify the development...

Annual or perennial, aquatic herbs, often bizarre in form, sometimes resembling lichens, bryophytes, seaweeds, or unlike any other plants; haptophytes, attached by adhesive hairs to rock or other hard objects in flowing freshwater, mostly in rapids and waterfalls; roots usually photosynthetic, creeping or partly floating, thread-like, ribbon-shaped...

The Podostemaceae (eudicots, Malpighiales) are adapted to rivers that exhibit distinct high-low water seasonality, mainly in the tropics. They attach to submerged rocks with ribbonlike or crustose green roots that cover the substrate like a carpet. Pronounced root dorsiventrality resulted in disklike crusts lacking root caps. African Podostemoideae...

Nymphaea and Nuphar (Nymphaeaceae) share an extra-axillary mode of floral inception in the shoot apical meristem (SAM). Some leaf sites along the ontogenetic spiral are occupied by floral primordia lacking a subtending bract. This pattern of flower initiation in leaf sites is repeated inside branching flowers of Nymphaea prolifera (Central and Sout...

Podostemaceae live as haptophytes in swift-running rivers with stony beds and seasonally changing water levels, mainly in the Tropics. The present study provides a comparative morphological study of eight Podostemum spp. including the former genus Crenias (P. comatum, P. distichum, P. irgangii, P. muelleri, P. ovatum, P. rutifolium, P. scaturiginum...

Developmental biology and evolutionary studies have merged into evolutionary developmental biology ("evo-devo"). This synthesis already influenced and still continues to change the conceptual framework of structural biology. One of the cornerstones of structural biology is the concept of homology. But the search for homology ("sameness") of biologi...

This paper complements the diagnosis of the recently described genus Diamantina and its only species Diamantina lombardii Novelo, Philbrick and Irgang from Minas Gerais (Brazil). Four new features not known from other Podostemaceae-Podostemoideae are documented by microtome sections and SEM graphs: (i) The digitate foliage leaves lack vascular tiss...

Despite an emphasis on fruit characters in Paullinieae taxonomy, few detailed morphological and anatomical studies of the gynoecia, fruits and seeds exist. The aims of the present study were (1) to provide a detailed documentation of gynoecium, fruit and seed structure and ontogeny in selected Paullinieae taxa; (2) to determine whether the gynoeciu...

New morphological and developmental observations are presented of Gunnera herteri (subgenus Ostenigunnera) which is, according to molecular studies, sister to the other species of Gunnera. It is an annual dwarf (up to 4 cm long) whereas the other Gunnera spp. are perennial and slightly to extremely larger. External stem glands are combined with cha...

The Neotropical genus Averrhoidium (Sapindaceae) is classified in Doratoxyleae (Radlkofer 1934) and comprises four species with disjunct distribution: Averrhoidium dalyi is found in east Peru and northwest Brazil, Averrhoidium gardnerianum in east Brazil, Averrhoidium paraguaiense in Paraguay, and Averrhoidium spondioides in west Mexico. All specie...

Podostemum ceratophyllum shows peculiar architectural characters that seem to apply to basal members of Podostemoideae. In contrast to more elaborate taxa of this subfamily, P. ceratophyllum fits into the classical root-shoot (CRS) model, with clearly distinguishable thread-like roots (with root caps and endogenous lateral roots), as well as stems...

In the genus Gunnera, the species of subgenus Panke are unique in having large, triangular scales between the leaves on the rhizomes. The morphological significance of these scales has been extensively debated in the past. They have been interpreted as stipules, ligules, or cataphylls, with attempts made to identify homologous structures in represe...

 Ledermanniella (c. 44 species) is the largest podostemoid genus in Africa. This paper deals with the structure and development of the Ghanaian species Ledermanniella bowlingii (J.B. Hall) C. Cusset (subgenus Ledermanniella). Characters typical for L. bowlingii include: green ribbon-like roots with exogenous lateral roots and endogenous shoots up t...

Pulsatilla vulgaris is a rare and endangered flagship species of dry meadows in Central Europe. The species decreased both in the number of populations as well as the respective sizes of the remaining populations in the last century. Fourtyfour populations were studied in north-eastern Switzerland between 1996 and 1998. Today they are rather small,...

We investigated the genetic variability within and among populations and the breeding system, germination and seedling survival in the remaining populations of the endangered Typha minima along the upper River Rhine. Isozyme analysis revealed low genetic differentiation among populations (mean genetic distance, D=0.03). However, the mean number of...

Saxicolella (six spp.) is a podostemoid genus occurring in tropical west Africa (Cameroon, Ghana, Nigeria). Taxonomically used characters such as root (with holdfasts), pollen (dyads in many Podostemoideae), capsules (with ribs) and seeds are demonstrated and discussed. This paper deals with the structure and development of two species, which are e...

Morphology and development of the female flowers in Geonoma interrupta are described and compared with other taxa within Arecaceae. Inflorescences are pleiothyrses. Cincinni are immersed in pits and arranged according to the Fibonacci pattern along the rachillae. The gynoecium is composed of three free carpels in early stages and later becomes pseu...

Cladopus (with 12 or less species) is an Asian and Australian genus of Podostemaceae–Podostemoideae. They are haptophytes that grow in rivers. The developmental morphology and anatomy of Cladopus austro-osumiensis Y.Kadono & N.Usui, C. austrosatsumensis Koidzumi, C. chinensis Chao, C. japonicus Imamura and C. queenslandicus [Domin] C.D.K. Cook & Ru...

This review compares new developmental models on flowering and other vascular plants with evolutionary hypotheses formulated by Agnes Arber (1879–1960) and like-minded botanists. Special emphasis is laid on philosophical basics such as perspectivism, pluralism about evolutionary modelling, continuum way of thinking, and fuzzy logic. Arber's perspec...

Cook, C. D. K. & Rutishauser, R.: Name changes in Podostemaceae. – Taxon 50: 1163–1167. 2001.‐ISSN 0040–0262. While preparing a review of the family Podostemaceae , we have found it necessary to change the name of some species. Following rules of priority, Crenias K. P. J. Sprengel replaces Mniopsis Martius. No convincing reasons can be found to ma...

Phyllotaxy (phyllotaxis) is the mode of arrangement of leaves, scales, or bracts with flowers along the plant stem. Phyllotaxy research deals with the study of biological pattern formation (morphogenesis); it answers questions such as what the shoot apical meristem (SAM) does and how it does it.

Apinagia (c. 50 spp.) is the largest genus of American Podostemaceae. Apinagia multibranchiata (Matth.) Royen is a haptophyte endemic to the Venezuelan Guyanas. It fits well with the Podostemoideae bauplan known from other New World genera, such as Marathrum and Mourera. Shoots arise in pairs from filamentous creeping adhesive roots. During the rai...

In vascular plants there are at least eight ways to develop polymerous whorls, i.e., whorls with four or more leaves. Six ways are presented and compared with literature to estimate organ identity (morphological significance) of the leaflike whorl members. New shoots (also seedlings) may start with dimerous or trimerous whorls. Then leaf number per...

Mourera fluviatilis from northern South America is a spectacular member of the Podostemaceae (river-weeds). Its raceme- like inflorescences are up to 64 cm long and have 40-90 flowers arranged in two opposite rows. Inflorescence development starts with the initiation of a double-sheathed (dithecous) bract in a terminal position. All lateral bracts...

Podostemaceae live in swift-running rivers with stony beds, mainly in the Tropics. This article is a comparative study of three Marathrum spp. (M. rubrum, M. schiedeanum, and M. tenue) and the monotypic genus Vanroyenella (with V. plumosa). The study is based on material from Mexico. Marathrum rubrum and V. plumosa are Mexican species, whereas the...

The annual Mediterranean herbTheligonum cynocrambe shows a peculiar combination of morphological characters, e.g., switch from decussate to spiral phyllotaxis with 90–100 divergence, combined with a change from interpetiolar to lateral stipules, anemophily, lack of calyx, flowers often dimerous to trimerous, corolla fused in both male and female fl...

Plant morphology, including morphogenesis, remains relevant to practically all disciplines of plant biology such as molecular genetics, physiology, ecology, evolutionary biology and systematics. This relevance derives from the fact that other disciplines refer to or imply morphological concepts, conceptual frameworks of morphology, and morphologica...

The structural and developmental diversity of the Podostemaceae is remarkable. A comparison of 19 genera (of 48 genera), and 27 species (of 270 species) is presented, covering both subfamilies, the Podostemoideae (= Pod.) and Tristichoideae (= Trist.). Assuming the Podostemaceae to be derived from a typical cormophytic plant with the classical root...

Leaves and stems of flowering plants have been widely accepted as clearly distinguishable structural categories. Evolution, however, can blur the stem–leaf (axis–appendage) distinction. Compound leaves with apical growth and three-dimensional branching may be seen as developmental mosaics sharing some growth processes with leafy stems (shoots). To...

Utricularia aurea Lour., an Old World aquatic of the section Utricularia, may produce a whorl of floats shortly above the base of the peduncle. If floats are lacking, they are replaced by rhizoids (resembling short shoots with claw-like subunits). A similar plasticity is found with respect to the dissected leaves along the watershoots (stolons), wh...

The following review summarizes new comparative ontogenetic studies on flowers and inflorescences in seed plants (including gymnosperms). With few exceptions, this discussion is restricted to literature published in the years 1989–1992. Emphasis is given on structural dynamics in ontogeny and phylogeny, on homeosis and heterochrony. Since the publi...

The developmental morphology ofIndotristicha ramosissima, a submerged rheophyte from South India, is described. Besides creeping organs (called roots) there are branched shoots with two kinds of short-lived photosynthetic appendages: scales and compound structures (called ramuli). These ramuli may be interpreted as leaf-stem intermediates because t...

The spiromonostichous phyllotaxy of Costus, and other Costaceae, is characterized by low divergence angles, often as low as (30⚬-) 50⚬. This constrasts with the main series Fibonacci (divergence angles approximating 137.5⚬) or distichous phyllotaxy found in all other Zingiberales. A morphological and developmental study of three species of Costus r...

In contrast to previous reports on reproductive structures (Progr. Bot. 47:52 ff; 49:51 ff), the following review will give special emphasis to dynamic and interdisciplinary aspects of reproductive structures (mainly flowers) in angiosperms. Not reviewed in this report are studies on embryology, palynology, pollination biology, seed dispersal, as w...

Reproductive structures, their development and evolution in the flowering plants (angiosperms) are the topics of this report. In surveying the last 2-year period (1985–1986) of publications, it becomes obvious that structural and developmental botany is an active and innovative field of research.

Habschr. Zürich (kein Austausch).