Figure 4

Schematic of a racemose inflorescence and an Aquilegia dichasial cymose inflorescence and AqLFY in situ expression patterns. In a racemose inflorescence (A), such as those of Arabidopsis and Antirrhinum, the apical meristem remains indeterminate. Secondary indeterminate inflorescences (coflorescences) may form in the axillary meristems of the first few nodes, followed by the production of determinate flowers in the subsequent axillary meristems. In the Aquilegia cymose inflorescence (B), the apical meristem produces two bracts with axillary meristems and then terminates in a flower. Secondary inflorescences develop from these axillary meristems. The secondary inflorescences also terminate in a flower with tertiary inflorescences developing in the axils of these flowers. This process repeats indefinitely. Expression of AqLFY in a pre-vernalization apical meristem (C), apical meristems four weeks into vernalization (D, E), apical meristems six weeks into vernalization (F, G), an apical meristem eight weeks into vernalization (H), a later inflorescence shown with three hierarchical degrees of floral and inflorescence meristems (I) and developing flowers at stage 7 (J) and stage 9 (K). Ap = apical meristem, Ax = axillary meristem, lf = leaf, b = bract, sp = sepal, p = petal, st = stamen, sd = staminodia, c = carpel. Solid arrowheads indicate location of incipient bract, open arrowheads indicate petal and stamen primordia. Asterisk in J: Due to the floral architecture of Aquilegia, the basal-most primordium in a vertical rank of organs may be a petal or a stamen. These are indistinguishable at early stages so we cannot differentiate between the two possibilities in this section. Scale bar = 50 μm C-D, I; 100 μm E-H; 200 μm J-K. sp = sepal,