Average spore lengths for specimens of  Argyrochosma ; error bars indicate one standard deviation. Symbol shading depicts the number of spores per sporangium (see inset legend). Lines beginning and ending in arrows indicate specimens observed to have two sporangia types, each with a different number of spores per sporangium.  The letter below each data point corresponds to a major monophyletic clade within  Argyrochosma . Sporophyte ploidy is indicated for documented chromosome count vouchers. Image from Sigel et al. 2011,  Systematic Botany.