CHAPTER III 



can easily learn to recognize because they can usually see that what 

 looks like a flower is really a flower-cluster. Plants of this family are 

 difficult to identify, and the teacher need not worry over ignorance in 

 this direction; but because total ignorance of names gives a feeling of 

 insecurity, the generic names of some common autumn Compositse 

 are given below. Everlasting plants (Gnaphaliums] take their popu- 

 lar name from their dry, silvery flowers ; their leaves are usually 

 very strongly scented and fleecy ; often the hair is denser on the 

 lower or stomata-bearing surface, but a covering of this sort on the 

 upper surface also is useful in lowering the temperature of the tran- 

 spiring cells within the leaves. Tar-weed is a name applied to 

 plants of several genera, such as Madia, Hemizonia, and Heterotheca, 

 and in general to Compositse that are strikingly viscid and ill-scented. 

 One large group of Compositae is characterized by milky juice and 

 ligulate or strap-shaped florets. The flower represented in Fig. 13, 

 Malacothriz tenuifolia, belongs to this group. The plant, in Southern 

 California, often grows six feet or more high, and in autumn it has a 

 very grey, lifeless appearance, except for the beautiful white, pink- 

 lined flowers that are open part of the day. Stephanomeria virgata 

 resembles this in general appearance, but is smaller and has heads 

 with fewer flowers inclined to a lavender tint. In many parts of the 

 state the sage brush or wormwood (Artemisia] "old man," the 

 children may call it abounds. Among the hills one may find golden 

 rod (Solidago), but more likely allied genera (Aplopappus and Bige- 

 lovia) with much stiffer habit, asters (either Aster or Corethrogyne), 

 the pretty Senecio Douglasii> with large, pale yellow, daisy-like 

 flowers, and fleecy, grey foliage, and sun-flowers (Helianthemum.) 

 Along streams there is a shrubby herb, Baccharis, with willow-like 

 leaves and small white flower heads, and so on, it would be impos- 

 sible to give anything like a full list. From this list the introduced 

 weeds, mentioned above, are omitted. The hoarhound not a Com- 

 posite is included in the collection because of its striking adapta- 

 tion to its environment, for besides its bitter taste and woolliness, it 

 has wrinkled leaves, a device for exposing less leaf surface to the 

 direct rays of the sun. 



The turkey- weed illustrates at least five uses of plant hairs ; for 

 defense (not all the stellate hairs are provided with little daggers, 

 only those situated so as to be specially effective), for protection 

 against light, dust and excessive transpiration, and finally for absorb- 

 ing water and what is dissolved in it. By no means all plant hairs 

 absorb moisture ; very often they are filled with air, and water enters 

 them with difficulty. Many hairy leaves, after immersion in water, 



25 



