For June, 1923 



151 



Plant Aggressiveness 



WILLARD N. CLUTE 



OXE does not have to possess a garden long to dis- 

 cover that phmts differ greatly among themselves 

 as to the ruggedness of their constitutions and the 

 measure of composure with which they endure adversity. 

 Looking through the dealer's catologue he may imagine 

 that all the treasures there described are equally easy of 

 cultivation but he soon discovers his mistake. One plant 

 will require every art to make it grow at all, while an- 

 other close by is so enterprising that if unchecked it 

 would soon take the garden to itself. From sad experience 

 we have learned better than to trust our tender young 

 onions, radishes and lettuces in the garden by themselves. 

 They get along very well together, it is true, possessing a 

 sort of well-bred repression that plants long accustomed 

 to the i)olite society of the garden should exhibit, but the 

 wild plants are of a less retiring disposition. Their motto 

 seems to be "get while the getting is good, and take all 

 you can." There is no ilanger that our cultivated plants 

 will spread out all over the garden, but there is a very real 

 danger that the garden will spread out all over them. 



We have dubbed these more aggressive wild species 

 "weeds" and have in many cases passed laws against 

 them, but this does not seem to bother them nuich. 

 The only legislation that appeals to them comes from 

 a sharp hoe in the hands of a determined gardener. 

 A weed has often deen defined as a plant out of place, and 

 so it is in most cases, but we have yet to discover what it 

 is that enables them to get out of place. First, of course, 

 comes the ability to spread rapidly into any region open 

 to them, and next comes the ability to hold what they have 

 taken. The first is usually accomplished by means of light 

 and easily transported seeds and the second by some 

 method of vegetative multiplicaliun. Plants with easily 

 distributed seeds, however, are not always pernicious 

 weeds, for many such have very little ability to hold the 

 ground against others. 



The worst weeds are usually those plants with effective 

 means of spreading in a locality after they have become 

 established in it, especially if they happen to be perennials 

 instead of annuals. In general, weeds have the additional 

 faculty of surviving all sorts of untoward conditions. 

 Our garden plants may i>erish in seasons of unusual 

 drougiit or cold but not the weeds. Although they may 

 be reduced consideraUy in numbers there are always 

 enough left to maintain the hope of the race. They have 

 waged war so long with the garden and the gardener, not 

 til mention wind and weather, that they are particularly 

 resistant. It is doubtful whether anybody ever really got 

 the best of a well established patch of quack grass. He 

 may fight it Summer after .Summer until the victory ap- 

 pears to have been won, but here and there, concealed by 

 the foliage of other plants or hidden entirely underground, 

 are certain small remnants that bide their time and as 

 soon as the gardener's vigilance is relaxed, back comes the 

 quack grass again ! 



Our consideration of what constitutes a weed is often 

 modified by considerations of how much it happens to be 

 out of place. Some plants, though regarded as weeds, 

 show so little hostility to our garden crops that it is hard 

 to work up much of a sentiment against them. A patch 

 of tansy along a country roadside is seldom spoken of in 

 disparaging terms. We look upon it with toleration or 

 perliaps with stronger feelings that are quite akin to 

 affection. It is a reminder of that mythical spot known 

 as "grandmother's garden" in which we mentally culti- 



vate all those well known plants with which we have been 

 associated from infancy. In this category, also, comes 

 catnip, and motherwort, and that other familiar plant 

 with fragrant leaves the costmary or bible-leaf, which 

 loves to make fragrant mats in out-of-the-way corners. 



It always makes a difference whose ox is gored. The 

 very qualities we abhor in the weeds, we commend in such 

 of our garden plants as possess them. Xo one ever had a 

 really fine peony that multiplied fast enough and the same 

 might be said of irises and many another. Still, one can 

 have too much of a good thing. A plant may lose its 

 reputation for beauty by becoming too common. This is 

 all that is the matter with the dandelion. If this plant 

 had to be carefully cultivated in order to bloom, we sin mid 

 all want a specimen to experiment with. The toad-flax 

 illustrates the idea very well, for it was originally a deni- 

 zen of the flower garden and not until it showed a disposi- 

 tion to multiply at the expense of its companions was it 

 thrown out to consort with other handsome floral vaga- 

 bonds like the crown vetch, the conuuon bell-flower and the 

 tawny day lily. The toad-flax appears to hold a hope that 

 it may again be admitted to the garden and, indeed, 

 occasionally pushes in among its more aristocratic friends, 

 but the crown vetch and the bell-flower have no such aspi- 

 rations and seem perfectly content to establish the colo- 

 nies by the roadside where they can see and be seen of all 

 men. 



The moneywort is fully as obnoxious as the toad-flax, 

 but by confining itself to the lawn and rooting at every 

 joint, it manages to escape eviction. A related species, 

 Lysimachia clethroides, is fully as aggressive but possess- 

 ing, as it does, a more beautiful truss of flowers and show- 

 mg a disposition to decorate wet and shady places, is 

 looked on with more toleration despite its tendency to 

 spread into new regions. 



It is difficult to say which is the worst, the Jerusalem 

 artichoke in the vegetable garden or the lily-of-the-valley 

 in the flower garden. The artichoke, like the quack grass, 

 is able to come back if an}' small bit is left in the soil. 

 Some in my garden has been coming back annually for 

 more than ten years. Sometimes it seems to be completely 

 eradicated but it manages to get into shape again by the 

 time vacation is over. 



The number of garden plants that spread all too rap- 

 idly is a large one. In many cases to introduce specimens 

 into cultivation is to provide one's self with a fairly con- 

 tinuous job for half a lifetime. The lily-of-the-valley, 

 though highly valued may easily become a pest among 

 other plants. If only the true lilies would multiply as rap- 

 idly ! I'he dame's violet has a tendency to appear in places 

 where it is not wanted and the day-flower (Commelina) is 

 a stubborn fighter. One of the evening primroses, 

 Fraseri, takes the ground like the toad-flax and has no 

 right to be included among other flowers. 



While aggressiveness is often a good trait, it is restful 

 to come back to those well-settled species, which, with no 

 disposition to spread, still maintain existence for a long 

 series of years untroubled by upstart weeds. The peony, 

 the gas plant, the yucca and many another will come to 

 mind in this connection. They do not have to be kept 

 within bounds ; they do not fail to come up each season 

 strong and serene. They are the joy of the gardener and 

 serveto keep up his courage when he is nearly over- 

 whelmed with less deserving species that plan to take the 

 garden awav from him. 



