Physaria brassicoides Rydberg 



DOUBLE BLADDERPOD 

 Mustard Family (Brassicaceae) 



CONSERVATION STATUS 



U.S. Fish and Wildlife Service: None 



Bureau of Land Management: None 



Montana Natural Heritage Program: G5 SI; demonstrably secure globally, but may be 

 critically imperiled in Montana where it is extremely rare. The global rank is recommended 

 for review because it may have been developed without due regard to the current taxonomic 

 treatment and associated distribution information. 



DESCRIPTION: Double bladderpod is a perennial herb that forms a basal rosette surmounting a 

 branched crown and large taproot. Basal leaves, 2-8 cm (1-3 in) long, are spoon-shaped, often with 

 wavy margins, and have long, somewhat winged petioles. Numerous stems, which ascend fi-om the 

 rosette, are 2-17 cm (1-6 in) long, with few, small (1-2 cm long), alternate, broadly lance-shaped 

 leaves. Foliage throughout is covered with silvery, star-shaped hairs. The flowers are borne on 

 pedicels at the top of the stems in a narrow inflorescence that elongates as the fruit matures. Each 

 yellow flower has 4 separate petals, 9-12 mm long, 4 separate sepals, six stamens, and a single pistil. 

 The bladderlike, inflated fruits (siliques) are 1 -2 cm long and at least as wide, and have two 

 chambers (locules) separated by a membranous partition (replum) which is narrow ( 1 mm wide) and 

 constricted towards the middle and obtuse at the apex. The silique is heart shaped (more indented at 

 the top than at the bottom where the two chambers meet). There are two ovules in each fiTiit chamber 

 and the style is 4-5 mm long. Flowering in May-early June, fruiting in June-early July. 



Physaria brassicoides is distinguished from other bladderpods primarily by fioiit characters (more 

 constricted above than below, 2 ovules per locule, and narrow, linear-shaped replum). The only other 

 bladderpod likely to occur in Carter County is the common bladderpod (P. didymocarpa; if indeed 

 their ranges overlap - see below). The latter has fruits that are about equally constricted above and 

 below (dumbbell-shaped), with 4 ovules per locule. Often ovules will abort so number of seeds is not 

 a reliable diagnostic character. Number of ovules can be determined by number of funiculi (the tiny 

 pegs which attach the ovules to the margin of the replum), which are persistent even if ovules abort. 



GEOGRAPHICAL DISTRIBUTION 



Global distribution: Western Great Plains; from western North Dakota to southeastern 

 Montana, south to western Nebraska and eastern Wyoming (Mulligan 1967, Rollins 1993, 

 Dom 1992, Heidel 1996). 



Note: The Great Plains Flora Association (1986) recognize just one species of bladderpod, 

 Physaria brassicoides Rydb., in the Great Plains, and treats P. didymocarpa (Hook.) A.Gray 

 as a synonym. It cites a Pacific Northwest and Rocky Mountain distribution for the taxon and 



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