Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-27T05:01:44.207Z Has data issue: false hasContentIssue false
  • English
  • Français

WHAT IS THE DITHECOUS LEAF? AN INVESTIGATION OF THE NEOTROPICAL PODOSTEMUM RUTIFOLIUM SUBSP. RICCIIFORME (PODOSTEMACEAE – PODOSTEMOIDEAE)

Published online by Cambridge University Press:  01 November 2009

I. Jäger-Zürn
I. Jäger-Zürn*
Affiliation:
Hainerbergweg 61, Königstein 61462, Germany. E-mail: irmgard.zuern@gmx.de
Get access

Abstract

The so-called dithecous leaves with two sheaths (adaxial and abaxial) which occur at branching in species of subfamily Podostemoideae of the aquatic flowering plant family Podostemaceae are enigmatic structures. The fact that in many species the shoot axes and leaves are fused has previously prevented an understanding of the real nature of dithecous leaves. This study reports on the position of the dithecous leaf in Podostemum rutifolium subsp. ricciiforme, the simple shoot structure of which has revealed that the dithecous leaf is the first leaf of the branch and does not arise from the main shoot as previously believed. Accordingly, the two sheaths of the dithecous leaf are interpreted anew: the sheath towards the branch, and its flower bud, is the true (ventral, adaxial) sheath of the dithecous leaf (formerly viewed as an additional new structure), and the other (dorsal, abaxial) sheath towards the flower bud of the main shoot of the branch is a novel structure. Consequently, the branch does not develop from the reverse side of the dithecous leaf in a subfoliar position, but rather is axillary above its subtending leaf. A similar structure was described in a previous paper on Apinagia riedelii, and in both species, and thus in subfamily Podostemoideae, the ramification pattern conforms to the pattern in other angiosperms.

Keywords

Dithecous leafleaf sheathnovel structurePodostemaceaeramification
Type
Articles
Information
Edinburgh Journal of Botany , Volume 66 , Issue 3 , November 2009 , pp. 469 - 481
Copyright
Copyright © Trustees of the Royal Botanic Garden Edinburgh 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Cook, C. D. K. & Rutishauser, R. (2007). Podostemaceae. In: Kubitzki, K. (ed.) The Families and Genera of Vascular Plants 9: 303–343. Berlin: Springer.Google Scholar
Engler, K. (1930). Reihe Podostemales. In: Engler, A. & Prantl, K. (eds) Die Natürlichen Pflanzenfamilien 18a: 1–68. Berlin: Duncker & Humblot.Google Scholar
Imaichi, R., Hiyama, Y. & Kato, M. (2005). Leaf development in the absence of a shoot apical meristem in Zeylanidium subulatum (Podostemaceae). Ann. Bot. 96: 51–58.CrossRefGoogle ScholarPubMed
Jäger-Zürn, I. (1994). Morphologie der Podostemaceae IV. Zur Kenntnis der dithekischen Blätter bei Podostemum subulatum Gard. (Podostemoideae). Beitr. Biol. Pflanzen 68: 391–419.Google Scholar
Jäger-Zürn, I. (1999). Developmental morphology of the shoot system of Podostemum subulatum (Podostemaceae – Podostemoideae). Beitr. Biol. Pflanzen 71: 281–334.Google Scholar
Jäger-Zürn, I. (2000). The unusual ramification mode of Sphaerothylax abyssinica (Wedd.) Warm. (Podostemaceae – Podostemoideae). Flora 195: 200–227.CrossRefGoogle Scholar
Jäger-Zürn, I. (2002a). Comparative studies in the morphology of Crenias weddelliana and Maferria indica with reference to Sphaerothylax abyssinica (Podostemaceae: Podostemoideae). Bot. J. Linn. Soc. 138: 63–84.CrossRefGoogle Scholar
Jäger-Zürn, I. (2002b). Morphology and morphogenesis of ensiform leaves in Apinagia multibranchiata and Mourera fluviatilis (Podostemaceae – Podostemoideae). Flora 197: 394–407.CrossRefGoogle Scholar
Jäger-Zürn, I. (2003). Comparative morphology as an approach to reveal the intricate structures of the aquatic flowering plant family Podostemaceae. Recent Research Developments in Plant Science 1: 147–172.Google Scholar
Jäger-Zürn, I. (2005a). Morphology and morphogenesis of ensiform leaves, syndesmy of shoots and the comprehension of the thalloid plant body in species of Apinagia, Mourera and Marathrum (Podostemaceae). Bot. J. Linn. Soc. 147: 47–71.CrossRefGoogle Scholar
Jäger-Zürn, I. (2005b). Structural analysis of the dissected leaves and shoot morphology of Marathrum foeniculaceum (Podostemaceae). Flora 200: 229–244.CrossRefGoogle Scholar
Jäger-Zürn, I. (2007). The shoot apex of Podostemaceae: De novo structure or reduction of the conventional type? Flora 202: 383–394.CrossRefGoogle Scholar
Jäger-Zürn, I. (2009). The ramification of Apinagia riedelii: a key to the understanding of the plant architecture of Podostemaceae, subfam. Podostemoideae. Flora 204: 358–370.CrossRefGoogle Scholar
Jäger-Zürn, I. & Grubert, M. (2000). Podostemaceae depend on sticky biofilms with respect to attachment on rocks in waterfalls. Int. J. Pl. Sci. 161: 599–607.CrossRefGoogle Scholar
Koi, S., Imaichi, R. & Kato, M. (2005). Endogenous leaf initiation in the apical meristemless shoot of Cladopus queenslandicus (Podostemaceae) and implications for evolution of shoot morphology. Int. J. Pl. Sci. 166: 199–206.CrossRefGoogle Scholar
Moline, P., Les, D., Philbrick, C. T., Novelo, A., Pfeifer, E. & Rutishauser, R. (2006). Comparative morphology and molecular systematics of Podostemum (including Crenias) – American river-weeds (Podostemaceae). Bot. Jahrb. Syst. 126: 427–476.CrossRefGoogle Scholar
Novelo, A. & Philbrick, C. T. (1997). Podostemum ricciiforme (Podostemaceae) rediscovered and redescribed. Taxon 46: 451–455.Google Scholar
Philbrick, C. T. & Novelo, A. (2004). Monograph of Podostemum (Podostemaceae). Syst. Bot. Monogr. 70: 1–106.CrossRefGoogle Scholar
Rutishauser, R., Pfeifer, E. & Moline, P. (2003). Developmental morphology of roots and shoots of Podostemum ceratophyllum (Podostemaceae: Podostemoideae). Rhodora 105: 337–353.Google Scholar
Warming, E. (1888). Familien Podostemaceae, Afh. III. Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd. ser. 6, 3: 446–514.Google Scholar