The Evolution of Diverse Floral Morphologies Edwige Moyroud, Beverley J. Glover  Current Biology  Volume 27, Issue 17, Pages R941-R951 (September 2017) DOI: 10.1016/j.cub.2017.06.053 Copyright © 2017 Elsevier Ltd Terms and Conditions

Figure 1 Modes of floral size variation in angiosperms. (A) The metre-wide corolla of Rafflesia arnoldii. (B) Brassica napus (rapeseed) and (C) Arabidopsis thaliana (thale cress) belong to the Brassicaceae family but the flowers of rapeseed are five times larger than those of thale cress. (D) Size difference between the flower of Nicotiana langsdorfii (left) and Nicotiana alata (right), two species of tobacco. (E) The flowers of Iberis sempervirens produce two small dorsal petals (red arrowheads) and two large ventral petals (stars). (F) Inflated calyx (white arrow), also known as the ‘Chinese lantern’ of Physalis alkegengi. Most rose cultivars (G) have hundreds of petals (one of those is labelled with a star) and very few stamens as a result of domestication and breeding, while their wild relatives (H) only display the 5 petals (stars) but numerous stamens (red arrowhead) characteristic of the Rosaceae family. (I) Flower size can vary during evolution when (1) the size of the floral meristem (FM) and/or the number of organ primordia produced change, (2) a conversion in floral organ identity occurs or (3) when cell proliferation or expansion mechanisms are modified. Example of genes involved in each of these three mechanisms are indicated: ULT, ULTRAPETALA; AG, AGAMOUS; MPF2, MADS-box Physalis floridana 2; POS1, Physalis Organ Size 1; BB, BIG BROTHER; IBR5, INDOLE-3-BUTYRIC ACID RESPONSE5. (J) The capitulum of Felicia heterophylla, an endemic daisy from South Africa, is an inflorescence that mimics the appearance of a solitary flower by gathering small tubular disc florets (a single disc floret is circled in red) surrounded by ray florets (a single ray floret is labelled with a black arrowhead) with showy petals. Picture credit: (A) Henrik Ishihara, (C) Stefan Lefnaer, (E) H. Zell, (F) Michael Gasperl via Wikimedia Commons. Current Biology 2017 27, R941-R951DOI: (10.1016/j.cub.2017.06.053) Copyright © 2017 Elsevier Ltd Terms and Conditions

Figure 2 Variations in floral organ shape. (A) Fused petals create the tubular corolla of Gasteria rawlinsonii. (B) Nectar spur of Impatiens noli-tangere. (C) Actinomorphic flower of Ipheion uniflorum. (D) Zygomorphic flower of Lobelia erinus. Axes of symmetry in C and D are indicated with dotted lines. (E) Bilateral calyx of Lupinus hirsutissimus (the large ventral sepal is indicated with a white arrowhead). (F) The flower of Yellow candlewood (Senna bicapsularis) produces three types of stamens: long ventral stamens (white arrow), lateral shorter stamens (black arrowhead) and dorsal staminodes (red arrow). (G) The flower of Calothamnus quadrifidus has fused red stamens (the filaments are fused but the anthers at the tip are not, two indicated by black arrowheads) that mimic a corolla and give the flower its claw appearance while (H) fused petals generate the cup-shape corolla of purple foxglove (Digitalis purpurea). (I) The corona (red arrow) of the blue passion flower (Passiflora caerulea) is a novel type of flower organ that forms between the petals (black stars) and the stamens (white arrowhead). (J) The flower of Mimulus cardinalis is pollinated by hummingbirds while Mimulus lewisii (K) is bee-pollinated. Picture credit: (B) Alpsdake, (E) Joe Decruyenaere, (H) H. Zell, (I) W. Robrecht, (J) Jason Hollinger, (K) David Monniaux, via Wikimedia Commons. Current Biology 2017 27, R941-R951DOI: (10.1016/j.cub.2017.06.053) Copyright © 2017 Elsevier Ltd Terms and Conditions

Figure 3 Creating diversity: changes in floral organ identity and visual display. (A) Organ identities are specified according to the classic (A)B(C) model in A. thaliana. The sliding (B) and fading (C) boundaries models are variations of the (A)B(C) model that explain organ identity specification in monocots (like Tulipa linifolia) and early diverging angiosperms (like Nymphea sp.), respectively. (D) The petaloid-bract of Cornus florida are due to ectopic expression of B-function genes. (E) The shape of epidermal cells (scale bar = 20 μm, adaxial epidermis of Nolana paradoxa petals), (F) the presence of pigment (unusual colour of jade vine flowers) and (G) non-pigment colours (gold metallic sheen of Bryophyllum tibuflorum) can combine with each other (H) to create striking visual patterns (complex petal spot of Gazania tenuifolia). Picture credit: (A) Alberto Salguero, (D) H. Zell, via Wikimedia Commons. Current Biology 2017 27, R941-R951DOI: (10.1016/j.cub.2017.06.053) Copyright © 2017 Elsevier Ltd Terms and Conditions