Plants recently established in the San Francisco 

 bay region 



Ira L. Wiggins 



In the truck gardening district of the Santa Cruz Peninsula 

 a few miles south of San Francisco, California, the representa- 

 tives of the introduced flora outnumber the native plants, at 

 least in number of specimens if not in species. Most of these 

 aliens are weeds that add nothing to the beauty of the region 

 and cause the farmers considerable trouble at planting and cul- 

 tivating time. Not one of these farmers intentionally introduces 

 a plant which he knows will increase the difficulty of keeping 

 his fields clean, nor does he welcome news of such an intro- 

 duction. Unfortunately the farmer seldom knows when some 

 insignificant seedling, appearing at the edge of the compost pile 

 or along a drive where hay from outside the state has been 

 hauled, may be the forerunner of a troublesome crop of weeds. 

 Thus many undesirable plant aliens become established before 

 anyone recognizes their potentialities for harm. 



But occasionally some particularly vigorous garden plant 

 escapes and becomes established along roadsides, streams and 

 irrigation ditches or in uncultivated fields. This sort of plant 

 seldom becomes a serious menace to the farmer's peace of mind, 

 and frequently adds enough to the beauty of the country side 

 to warrant putting up with some inconvenience incurred with 

 its presence. 



A plant of each type has recently gained a foothold in the 

 rich soil of the peninsula and both bid fair to become permanent 

 members of our naturalized flora. Along the Skyline Boulevard, 

 between Colma and the ocean, Oxalis cernua has established 

 itself in several fields so thoroughly that the masses of yellow 

 flowers brighten the whole hillside and attract the attention of 

 motorists who stop to pick huge bouquets. Sometimes a Jap- 

 anese florist may be seen picking the flowers to sell in his road- 

 side booth. 



Oxalis cernua Thunb. is a native of South Africa, but is used 

 extensively in California as a garden ornamental. Although it 

 escapes at a number of places throughout the state it does not 

 seem to do as well at any of these localities as it does near 

 Colma. It is not at all likely that it will become a bothersome 



