Lotus burtii and Cassia roxburghii

Well, my apologies all. Life and work have been very much getting in the way, so today’s entry will be one to belatedly conclude the series for UBC’s Celebrate Research Week.

Lindsay introduces today’s author:

Dr. Quentin Cronk is a Professor in Plant Science at UBC’s Biodiversity Research Centre where he works on flower evolution in legumes and the genetic factors that underly these morphological changes. Together with his PhD student Isidro Ojeda they have investigated the distribution of epidermal types in petals of legumes and how this feature has evolved within the family.

Dr. Cronk writes:

The first picture (A) depicts the distribution of the epidermal types in a “papilionoid legume” with a typical pea-type flower, Lotus burtii. The second picture (B) depicts the same in a “caesalpinioid legume” with a caesalpinoid flower, Cassia roxburghii. The latter is thought to be a more primitive flower type. The epidermal photographs were taken using a scanning electron microscope (SEM) of fresh petals that were put directly into the microscope.

Pea-flowers, exemplified here by Lotus burttii, have three distinctive types of petals, one upper (dorsal), two side (lateral) and two lower (ventral) petals. Each petal type has a different role during the flower-pollinator interaction. For instance, due to its position within the flower, the upper petal is highly visible and acts to attract pollinators, while the side petals in papilionoid flowers are mostly used as landing platforms for bees.

Ojeda and Cronk found, in a survey of 175 species, that most pea-flower types have the distribution of epidermal types depicted in figure A. Each petal type has a specific surface structure that gives each petal its own unique identity. For instance the bumpy surface of the upper petal reflects light in a way that makes the petal brighter and more attractive to bees.
In contrast, legumes with a caesalpinoid-type flower do not have this diversification of epidermal types within the flower. The different types of petals cannot be differentiated at the epidermal level. This also applies in the redbud (Cercis canadensis), which has a flower that looks like a pea-type flower, but in fact it is a caesalpinioid legume, and the petal surfaces confirm this.

This survey has allowed the identification of major epidermal types and the general trends of its evolution within the family. Furthermore, it allows us to study the link between the underlying genetic controls (petal identity genes) and petal morphology. We are applying this to understand the evolution of related legume species with very different flower types, for instance in the transition from bee to bird pollination, as described in a previous UBC Research Week.

This broad survey would not have been possible without the living plant collections of botanical gardens. For this study we used the collections of the UBC Botanical Garden, the Fairchild Tropical Botanical Garden in Florida, USA and the Jardín Botánico Regional at CICY, Mexico.

For more details of this work, please see the published paper: Ojeda et al. 2009. Evolution of petal epidermal micromorphology in Leguminosae and its use as a marker of petal identity. Annals of Botany 104(6):1099-1110. doi:10.1093/aob/mcp211.

Lotus burtii
Cassia roxburghii

18 responses to “Lotus burtii and Cassia roxburghii”

  1. vicki t.

    Wow – That’s amazing. I love reading this type of information. Thank you for ALL of your entries!

  2. Susanne

    wow, beautifully taken micrographs!!

  3. fool4jesus

    I found your site by accident wandering around Drudge Report. I’m so glad I found it! I am daily amazed at the creativity of God our Creator. My other daily web site is “Astronomy Picture of the Day”. I’ve been with that one going on 10 years. Hope to be on this one as long. Thanks!

  4. Daniel Mosquin

    Please note that you are asked to share your comments about the photographs and the accompanying write-up, not to proselytize or to assume on behalf of an international readership that everyone follows the same religion, if any at all.
    In other words, we stick to science here, including evolution. There are many places on the web to disagree with science however you want, but Botany Photo of the Day isn’t one of them.

  5. Denise

    Proselytizing because of one statement!!?? That’s hilarious . . . If that gets your panties in a twist, you need to lighten up, dude! Methinks you are WAY too strung up.

  6. Daniel Mosquin

    It’s because I have neither the time nor the desire to have an extended discussion on the issue.
    Comments like yours, and mine in response to yours, only serve to continue this discussion in a manner that takes it away from the photograph and write-up.
    Let’s get it back on topic, please.

  7. Anaster

    I agree that it’s important to keep all religion comments, both large and small, out. It’s just opening up a grotesque can of worms, so to speak. Can’t we simply have fun and enlightenment sharing our thoughts on the plants under discussion and our reaction to the gorgeous images displayed without turning the forum into a bully pulpit for a few?

  8. Robert Frost

    Awesome pictures. I love ’em.

  9. elizabeth a airhart

    daniel when you all post on the blog that
    kew gardens thinks tomato plants are killer
    plants my paronia is up 100 percent in the
    produce section of the market si fi film to come
    thank you for the entry pictures are so good
    a lot of time and talent went in to the entry
    did you all see the species of the day
    the photo is just great bottom of the page
    really folks i agree with with daniel we learn
    and have fun if you stay away from
    killer petunias that is

  10. Daniel Mosquin

    Elizabeth, I have just recently — not on BPotD, though: The “New” Carnivores.

  11. elizabeth a airhart

    thank you i did read it on your web blog
    left hand side of your page

  12. Cambree

    Wow! Makes you stop to think about it more now. Thanks for the close up.

  13. Gabrielle

    Fantastic pictures! So much to learn about plants…the more we know the less we know!
    Is there any way to tell the difference between the two types of legume flowers without the elctron microscope?
    Thanks again for the beautiful and informative BPoTD.

  14. Sheila

    Fascinating pics and research. Thank you.

  15. Robin Winburn

    Thank you for these awesome closeup details! Beautiful and a special treat that we don’t get to see under daily circumstances!

  16. bonniel

    Sometimes I read things like this and realize how little I know. Right now I not sure of the questions to find what I don’t know. Keep up the good work nnd maybe some day it will click in. THANK YOU

  17. Sparganium

    Being both a plant geek and a word nerd, I’m curious about the etiology of the term caesalpinioid (with papilionoid meaning “butterfly-like”).

  18. Daniel Mosquin

    Sparganium, it’s actually named after a person, Andrea Cesalpino, an Italian botanist.

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