Brassicaceae: Mustard Family — Cress
Members of the mustard family all have four petals, usually in a cruciform shape (hence Cruciferae; the old name for the family). With some groups (particularly the mustards themselves (Brassica, Hirschfeldia, Sisymbrium, Caulanthus and Turritis)), it is necessary to pay close attention to the fruits. Fruits in the Mustard family are of two kinds, siliques and silicles. Siliques are typically at least 2 x as long as they are wide and silicles are not. Some siliques are more or less cylindric, others (as in the Wild Radish) are noticeably fatter at the base and taper towards the tip. Some silicles are erect and appressed to the stem, others grow outwards and curve upwards or outwards and curve downwards. Recognizing these different characteristics makes it much easier to identify species which may have very similar flowers.