Missouri Botanical 

 Garden Bulletin 



Vol. IX St. Louis, Mo., February, 1921 No. 2 



TRAPA BICORNIS (BULL'S HEAD) 



Recently visitors have brought to the Garden for identifi- 

 cation seeds, purchased in St. Louis and represented to be 

 those of a large-flowered water-lily equal in size to the Easter 

 lily and having either white or pink flowers. This has been 

 identified as Trapa bicornis, or bull's head, a species most 

 interesting from the standpoint of mimicry, the seeds closely 

 resembling a bull's head in shape. 



This plant is indigenous to the shallow rivers and un- 

 drained marshes of China, where it is cultivated very exten- 

 sively as a substitute for corn. In the young state the plant 

 is submerged, the seeds germinating in the muddy bottom of 

 a stream or lake. The primary shoot or radicle appears be- 

 tween the horns, and from this the roots extend, penetrat- 

 ing the soil and attaching the young plant to the mud. The 

 foliage consists of two distinct types: first, the submerged 

 leaves, which are linear and somewhat resemble roots in 

 shape ; second, the floating or air leaves which appear when 

 the plant reaches the surface of the water. The latter are 

 rounded, about three-quarters of an inch across, the upper 

 surface of a light green color, the under side purple and 

 hairy. The petioles, which support the leaves, contain spongy 

 pith which makes them buoyant. The flowers are small, sol- 

 itary, of a pellucid white color, comprised of four petals 

 about an inch in width. The peduncles which support them 

 bend when the flower drops, thus allowing the seed to ripen 

 under water. The basal portion of the seed, which represents 

 the mouth of the bull, is the connection between seed and 

 plant. Therefore, in ripening the horns are reversed. The 

 natives of China call the seeds "ling." 



In 1781 Solander introduced the southern European 

 species, Trapa natans (water caltrops), into northern France 

 and attempted to bring it to fruit in the open air, but failed. 

 At a later date, Lambert, of Boyton, England, succeeded in 

 ripening seeds under greenhouse treatment. The genus was 

 named by Linnaeus from calcitrapa, or caltrops, an instru- 



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