Fig. 1. A comparison of different cell types in Arabidopsis (ecotype Landsberg erecta) wild type and the crooked mutant. (A) Two or three branched, stellate wild-type trichomes. (B) Randomly shaped, distorted trichomes in crooked with unextended branches (arrow) located in aberrant positions. (C) Typically elongated cells occupy the mid-zone of wild-type hypocotyl in 10-day-old seedlings. (D) The hypocotyl mid-zone of 10-day-old crooked seedlings shows radially expanded cells and a lack of the file arrangement observed in wild type. (E) A hypocotyl of 7-day-old wild-type seedling displays clearly differentiated stomatal complexes (arrows). (F) A hypocotyl of a 7-day-old crooked seedling does not possess stomatal complexes in the characteristic regions. (G) The typical epidermal surface of expanding wild-type cotyledons patterned into a jigsaw puzzle shape through cell-lobing. (H) Cotyledon-cells in crooked are less expanded compared with the wild type and are impaired in lobe formation. (I) Hypocotyl of wild-type seedling challenged to elongate rapidly by growing in dark for 7 days show a regular arrangement of cell files with each cell firmly in contact with its neighbors (arrows at cell junction). (J) The hypocotyl of a crooked seedling challenged into rapid elongation became scruffy as cells broke contact with their neighbors along the long axis and curled outwards (arrows) to leave gaps in the epidermis. (K) Wild-type root hairs are straight, tubular and can elongate up to 1 mm. (L) Root hairs in crooked are 1.5- to 2-fold thicker than wild-type hairs, are sinuous (arrowheads) and can display varying diameters along their length. (M) A single trichoblast in crooked showing aberrant development of two root-hair initials (arrowheads). Numbers given below scale bars are in µm.