Glandular Hairs of the Ovary: a Helpful Character for Asteroideae (Asteraceae) Taxonomy?
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Ann. Bot. Fennici 44: 1–7 ISSN 0003-3847 Helsinki 16 March 2007 © Finnish Zoological and Botanical Publishing Board 2007 Glandular hairs of the ovary: a helpful character for Asteroideae (Asteraceae) taxonomy? Daniela Ciccarelli*, Fabio Garbari & Anna M. Pagni Department of Biology, University of Pisa, via Luca Ghini 5, I-56126, Italy (*corresponding author’s e-mail: [email protected]) Received 19 Dec. 2005, revised version received 9 June 2006, accepted 14 June 2006 Ciccarelli, D., Garbari, F. & Pagni, A. M. 2007: Glandular hairs of the ovary: a helpful character for Asteroideae (Asteraceae) taxonomy? — Ann. Bot. Fennici 44: 1–7. Surface microcharacters of the ovary of the Asteraceae were studied, especially biseriate glandular hairs. Of 34 species belonging to the Asteroideae, only Dittrichia viscosa, Pulicaria dysenterica, Bellis perennis, Tanacetum parthenium, Achillea mar- itima, Matricaria chamomilla, and Eupatorium cannabinum possess glandular hairs on the ovary. Additional characters considered are hair morphology and distribution, cell number, and presence of subcuticular chambers and chloroplasts. The usefulness of glandular hairs of the ovary for taxonomic purposes is discussed. Key words: Asteraceae, Asteroideae, glandular hairs, light microscopy, ovary, SEM, taxonomy Introduction (Ascensão et al. 2001).Investigations referring to a supraspecific taxon are scarce. Carlquist (1958) In the Asteraceae both non-glandular and glandu- analysed the structure and ontogenesis of glandu- lar hairs are present (Metcalfe & Chalk 1950). The lar hairs of Madinae, demonstrating their taxo- non-glandular hairs are represented by numerous nomic and evolutionary significance. Napp-Zinn morphological types, whereas the glandular hairs and Eble (1980) took into consideration the glan- are more homogeneous. The latter are usually dular and non-glandular hairs of twenty genera of formed of a peduncle and a head of one or many the Anthemideae. In the genus Artemisia, features cells. The most common type, found in numerous of the glandular hairs are considered useful for species, is a biseriate hair formed of five pairs of the separation of A. nova from A. arbuscula and cells. Detailed studies of this type of hair, its mor- A. tridentata (Kelsey 1984). phology and ultrastructure have been carried out Glandular hairs, in the Asteraceae, may be on plants of economic interest, such as Dittrichia present both on the vegetative and floral parts. viscosa (Werker & Fahn 1981), Artemisia annua In the capitula they are found on the receptacle, (Duke & Paul 1993), Artemisia nitida (Corsi & bracts, corolla and also on the ovary. On the Nencioni 1995), Artemisia campestris (Ascensão ovary surface, other types of hairs may also be & Pais 1987), Achillea millefolium (Figueiredo & present: twin hairs, of a characteristic double Pais 1994), Helichrysum aureonitens (Afolayan structure, and slime hairs, usually multicellu- & Meyer 1995), and Helichrysum stoechas lar, involved in the production of mucilaginous 2 Ciccarelli et al. • ANN. BOT. FENNICI Vol. 44 material (Roth 1977). The characters of the sur- for the phylogeny and classification of the family face of the ovary and fruit have repeatedly been is underlined in several recent works (Ander- used for the delimitation of taxa at various levels berg 1991, Karis 1993, Zhang & Bremer 1993, in several families (Karcz 1996, Lane 1985). Bremer 1994). The present paper is a contribu- However, in the Asteraceae they are seldom used tion to the study of the surface microcharacters as key characters in floras, and when they are, of the ovary, focusing on biseriate glandular the different types of hairs are only occasionally hairs. Its particular aim is to verify, through considered. The importance of cypsela features examples, the potential usefulness of glandular hairs for taxonomical and phylogenetic studies. Table 1. Species of subfamily Asteroideae collected from Migliarino-San Rossore-Massacciuccoli Natural Park. Species marked with an asterisk (*) possess Material and methods glandular hairs on the ovary. Tribe Species The plant material examined originated from a protected area (Migliarino-San Rossore-Mas- Inuleae sacciuccoli Natural Regional Park, Pisa, Italy) * Dittrichia viscosa (L.) Greuter characterised by a high biological diversity. Inula conyzae Griesselich Limbarda crithmoides (L.) Dumort. Restricted by the Park regulations, we randomly * Pulicaria dysenterica (L.) Bernh. collected capitula from at least five individual Pulicaria odora (L.) Rchb. plants of each species during the flowering and Pulicaria sicula (L.) Moris fruiting phases (years 2001–2003). The spe- Gnaphalieae cies studied are listed in Table 1. The 34 spe- Filago pyramidata L. Filago germanica L. cies examined belong to seven tribes: Inuleae, Gnaphalium uliginosum L. Gnaphalieae, Astereae, Anthemideae, Senecio- Helichrysum italicum (Roth.) Don. neae, Heliantheae, Eupatorieae (classification Helichrysum stoechas (L.) Moench and nomenclature in accordance with Bremer Astereae 1994 as modified by Greuter 2003a, 2003b, Tripolium pannonicum (Jacq.) Dobrocz. * Bellis perennis L. 2003c, Greuter et al. 2003). Erigeron canadensis L. Erigeron acris L. Erigeron karwinskianus DC. Light microscopy (LM) Anthemideae * Tanacetum parthenium (L.) Sch.-Bip. Artemisia coerulescens L. Sections (25 µm) of fresh capitula were cut using Achillea millefolium L. a Leitz 1720 cryostat at –14°/–16°C. Other sec- * Achillea maritima (L.) Ehrend. tions (3 µm) were cut using a Leica 2055 micro- Anthemis arvensis L. tome, after fixing the material in FAA (Sass Anthemis cotula L. 1958) and embedding it in LR White acrylic Coleostephus myconis (L.) Cass. Leucanthemum pallens (Gay) DC. resin (SIGMA). All the material was stained Leucanthemum vulgare Lam. with Toluidine Blue (TBO) (O’Brien & McCully * Matricaria chamomilla L. 1981), a generic dye for DNA, cytoplasm and Senecioneae some cell wall components. Jacobaea erratica (Bertol.) Fourr. Fresh material was also observed under a light Senecio lividus L. Senecio vulgaris L. microscope without any staining procedure. Heliantheae Bidens frondosa L. Bidens tripartita L. Scanning electron microscopy (SEM) Xanthium italicum Moretti Xanthium strumarium L. Eupatorieae All the material was fixed in glutaraldehyde (2% * Eupatorium cannabinum L. with buffer solution at pH 7.4), dehydrated in a gradient of an alcohol and acetone mixture, criti- ANN. BOT. FENNICI Vol. 44 • Glandular hairs of the ovary: a helpful character for Asteroideae taxonomy? 3 cal point dried and sputter-coated with gold. The samples were examined at 15 KV using a Cam- bridge Stereoscan 90 SEM. Results Biseriate glandular hairs were found on the ovary of Dittrichia viscosa, Pulicaria dysenterica, Bellis perennis, Tanacetum parthenium, Achillea maritima, Matricaria chamomilla, and Eupato- rium cannabinum. The typical base model (made up of ten cells: two basal cells, two of the pedun- cle and six of the secretory head) is present on the ovary of B. perennis, T. parthenium, A. maritima, M. chamomilla and E. cannabinum. In B. perennis and in E. cannabinum the number of head cells varies from six to eight, in D. viscosa and in P. dysenterica each series of the head hair is formed of six to nine cells; the apical cells are very large (Fig. 1). The hair morphology does not show any within-species variation. The hairs can be distributed on the whole Fig. 1. Biseriate glandular hairs. — A: Dittrichia vis- surface of the ovary as in D. viscosa, in B. peren- cosa (scale bar = 18.3 µm). — B: Pulicaria dysenterica nis and in E. cannabinum (Fig. 2A–C); between (scale bar = 8.3 µm). — C: Bellis perennis (scale bar = the ribs as in T. parthenium, A. maritima (Fig. 3.4 µm). — D: Eupatorium cannabinum (scale bar = 4.6 µm). — E: Tanacetum parthenium (scale bar = 4.1 µm). 2D, E) and M. chamomilla (A. Andreucci pers. — F: Achillea maritima (scale bar = 2.6 µm). — G: Mat- comm.); and in the apical part of the ovary as ricaria chamomilla (scale bar = 3.0 µm). Chloroplasts in P. dysenterica (Fig. 2F). The hair distribution are present in all the cells of the head with the excep- pattern seems to remain constant within a spe- tion of the apical cells, in B. perennis also the apical cies. cells have chloroplasts. The shape of the hair tip can vary from glob- ular in T. parthenium (Fig. 3A) to fungiform in E. cannabinum (Fig. 3B), more or less clavate in In the species studied, chloroplasts are B. perennis (Fig. 1) or cylindrical in D. viscosa present in all cells that form the head of the hair, (Fig. 3C) and in P. dysenterica (Fig. 3D). except in the apical cells; in B. perennis also the All glandular hairs have, at full growth, a apical cells are green. subcuticular chamber, a space coming out when When the fruit matures the glandular hairs the two layers of the cuticle become detached remain, but their structure often degenerates. from the pecto-cellulosic wall (Fahn 2000). Its size can be very different among species while being usually uniform within a species. Among Discussion the plants analysed, B. perennis has the smallest subcuticular chamber (Fig. 1C) with regard to The classification of Asteraceae remains in a only the apical cells; E. cannabinum has a bigger state of flux. In a revision of the family, Bremer chamber that gives the hair a fungiform appear- (1994) pointed out that, to provide a complete ance (Fig. 3B); a large spherical chamber is also classification, new research and taxonomic revi- present in D. viscosa, P. dysenterica and A. mar- sions were necessary especially at the lower itima. In the last species the chamber regards not taxonomical levels. Even if molecular research only the apical but also the lower cells (Fig. 1F). has provided an important contribution to under- 4 Ciccarelli et al. • ANN. BOT. FENNICI Vol. 44 Fig. 2. — A: Dittrichia vis- cosa: few glandular hairs (arrows) are distributed on the ovary among non-glan- dular hairs (scale bar = 100 µm). — B: Bellis perennis: biseriate glandular hairs (arrows) are distributed on the whole surface of the ovary (scale bar = 80 µm). — C: Eupatorium cannabi- num: glandular hairs are distributed on the whole surface of the ovary (scale bar = 130 µm).