Highlights from 2008

VIRTUAL POSTER SESSION
2008

Comparative ontogeny of compound leaves:
deciphering the enigmatic 3-parted leaf
of the bishopwood tree
(Bischofia; Phyllanthaceae)

Ana Marcela Florez
Research Training Program, 2008

Introduction

Based on leaf architecture, there are three main compound leaf types: pinnate, palmate, and ternate (White. 2005.) The origins of ternate leaves are unclear, they might be derived by reductions from pinnate or palmate forms, there are no phylogenetic hypotheses of closely related pinnate or palmate taxa from which to determine the direction of any changes (Wurdack, K. J. et al. 2004). The origins of compound leaves can be revealed through their early ontogeny and the study of mutant leaves. In Bishofia javanica and Staphylea holocarpa, leaf mutants have been found that present multi-leaflet pinnate and palmate forms

This study focuses on the bishop tree (Bischofia) with an odd asymmetrical ternate leaf that has been proposed to be of pinnate derivation (Airy Shaw, 1967). The objectives of this research were: Describe anatomical features in Bischofia and to compare and analyze the early ontogeny of compound leaves with a focus on three-parted, ternate, leaves.


Results & Conclusions

In Bischofia and Staphylea holocarpa, mutant mature leaves were found with mixed multi-leaflet pinnate and palmate forms. Development of extra leaflets in the latter taxon was acropetal in the manner of pinnate leaves. The leaves of Bischofia showed no further axis growth after the near simultaneous initiation of the lateral leaflets. Laminar domatia in Bischofia did not reveal any secretory regions that might indicate a reward for the mites they putatively house.


Schematic diagram of the early ontogeny of the different kinds of compound leaves.

1. Inception of the leaf primordium on the shoot apex

2. Formation of the first pair of lateral leaflet initials on the leaf primordium

3. Three-parted compound leaf organization in ternate leaves

4. Ternate characteristic leaf development in Bischofia javanica

5. Successive elongation of leaf axis and acropetal sequence of the formation and development of leaflet initials in pinnate leaves

6. Acropetal sequence of formation of mutant leaves with the appearance of the second pair of leaflets in Staphylea holocarpa

7. basipetal sequence of formation of the second pair of leaflets

8. Second pair of leaflets in basipetal position in Joannesia princeps

Leaf development from inception to maturity of the three-parted leaf of Bischofia javanica.

1-2. Leaf primordium growth with no differentiation of leaflets

3-4. Cross section through a shoot tip, two leaves L1 and L2 in early stages of development, a stipule S protects one leaf

5-6. Leaflet initials originating on the margin of the leaf primordium

7. Complete shoot tip with more advanced stages of development, stipules are visible

8. Cross section on complete shoot tip showing several stages of leaf development

9. Unexpanded leaf in further stage of development

SEM images of early stages of the three-parted leaves of Staphylea holocarpa.
1. Leaf primordium with no differentiation

2. Leaf primordium with differentiation of the terminal leaflet

3. Differentiated terminal leaflet and lateral leaflets

4. First pair of leaflet initials growing upwardly, the second pair of mutant leafs is developing above the first pair

5-8. Progressively elongated first and second mutant pair of lateral leaflets, for a total of 5 leaflets

Details of Bischofia foliar morphology.

1. Marsupiform leaf domatia, cross section from near entrance

2. Central part of domatia

3. Near terminus of domatia, also note the lack of secretory tissues in domatia

4. SEM photomicrograph of domatial entrance

5. Theoid teeth present on the leaf margin

6. Domatial entrance.

Acknowledgements

We would like to thank Max Berry’s generous donation to the 2008 Research Training Program (RTP) of NMNH, which made possible first author participation. J.C. Raulston Arboretum and at the US National Arboretum provided some samples. Our sincere gratitude to S. Yankowski, S. Whittaker, M. Sangrey and the 2008 RTP class for their assistance and support.



Smithsonian Institution
National Museum of Natural History
Research Training Program

The information presented here, as part of the Research Training Program Virtual Poster Session, represents preliminary data as the result of ten-weeks of investigation in-residence at the National Museum of Natural History. This is not an official publication nor are the finding presented here necessarily conclusive or definitive.

As preliminary information, these results and/or findings should not be cited as part of conclusive work. Please contact the author if you would like further information about this research as well as the resulting scientific publication and/or presentation.