6 University of California Publications in Botany [^ol. 7 



of size variation of the eastern and western forms of T. sessile prob- 

 ably overlap slightly, but also that the average individual of the 

 eastern form is throughout strikingly diminutive as compared with 

 its Californian variety. Tluis, with reference to length of petal, 

 a very small percentage of the more than five hundred flowers meas- 

 ured have fallen below 4 cm., while 6 to 7 cm. represents perhaps the 

 average length and many measurements show a length of over 8 cm. 

 The relatively few specimens of the eastern sessile examined give 



4 cm. as the maximum and 1.3 cm. as the minimum length of petal. 

 One other size difference might be mentioned, i.e., leaf size. Accord- 

 ing to our limited observation, the eastern species bears leaves not 

 over 8 cm. long and always longer than broad, while the smallest 

 specimen measured showed leaves only 4.2 cm. in length. Possibly the 

 largest leaf of the western form observed was 17.5 cm. in length 

 and its greatest width was 19.5 cm. An excess of width over length 

 of leaf is not unusual and may even be characteristic of tlic ])lants 

 from certain localities. The minimum length of leaf approximates 



5 cm. in one specimen. In this matter of leaf size we are referring 

 only to normally flowering plants of mature structure. It may in 

 general be said that T. sessile var. giganteum exhibits a most remark- 

 able range of variation as to the size of all characters both vegetative 

 and floral. This situation is illustrated in plate 2, figures 3 and 4, 

 and is sufficiently striking to make unnecessary further comment here. 

 Variations in form and shape of corresponding characters are brought 

 out in these same plates. With reference to this matter of form and 

 shape variation we again prefer to postpone the presentation of the 

 complete data until it may be possible to consider together in full 

 the relation of size, shape and color forms peculiar to definite localities. 

 That the range of variation in shape and form of vegetative and 

 floral organs is as great as their size differences should be sufficiently 

 apparent from the specimens shown in plates 3 and 4. An extreme 

 variation with respect to width of petal is the {T. sessile) variety 

 angustipetalum of Torrey. This extremely narrow-petalled form 

 represents simply a point in the very wide range of variation in petal 

 width peculiar to the species in California, although it may, as 

 reported, be characteristic of certain definite localities — i.e., the 

 Sierra Nevada — though on plants growing at 3500 feet near Dutch 

 Flat, Placer County, the petals were rather broadly ovate. 



With reference to the nature of the apparent gigantism of T. 

 sessile var. giganteum we have some more or less fragmentary cyto- 



