The brilliant appearance of our western roadsides and prairies from July to October, invites an extended study of the anatomy and physiology of the Compositae. The wide distribution and rapid increase of this family naturally call attention to dissemination and pollination. Darwin, Herman Mueller, and others, have shown at length, the direct relation between special adaptations for cross-pollination and the race stability of plants. The question now arises, what are the opportunities for cross-pollination in Compositae, and to what extent is this agent a factor on the increase and distribution of the family? No attempt is here made to go into a discussion in full of these questions for the entire Family, but simply to present a few facts relative thereto, gathered from representatives of the subtribes Heliantheae and Asterineae

Nichols, Mary Alice

English

University of Northern Iowa

Proceedings of the Iowa Academy of Science Volume 1 Part 4, 1893; (1887) - Article 31 1893 Observations on the Pollination of Some of the Compositae Mary Alice Nichols Copyright ©1893 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Nichols, Mary Alice (1893) "Observations on the Pollination of Some of the Compositae," Proceedings of the Iowa Academy of Science, 1(Pt. 4), 100-103. Available at: https://scholarworks.uni.edu/pias/vol1/iss4/31 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. 100 IOWA ACADEMY OF SCIENCES. Sphegidae: C1 ab,-o sp. Ammophila conditOI'. Ichne11111011ir1ae: Tryphon sp. Lana montana (?) Coleopterct Meloidae: Epicauto Pennsylwnica feeding on pollen. Hemiptera- Phymata Wolfii. Diptera- Jfusciclae: Stomoxys. Meso-grapta marginata. Cnicus altissimus. vVilld. Var. discolor. Gray. Visitors. HYMENOPTERA-Apidae: Bomlnts fel'Vid11s, B. A1uel'ican11s, B. vagans. .lfegachile centuncularis .Apis mellifica, Ce1·atina dupla, Melissodes bimaculata. ~ISCELLANEOUS PLA~TS. Polygonum acre. H. B. K. Small spiked flowers. Insects are attracted by its pinkish color. Flowers perfect. Visitors-DIPTERA-Muscidae: Cal/iphora rnmitoria. HY)IENOP'l'ERA-Apidae; IIalictus tegularis. Calliopsis andreniformis, P1111pla inquisitor. Sphegidae; Ammoµhila conrlitor. HnrnNOP'l'ER . \ feed on honey secreted at the base of the corolla, wlnle DrPTERA feed on both nectar and pollen. Serl11m Telephium, L. :!!'lowers-compound cymeR; petals white. Visitors-H YME:'\OPTEHA-Apidae: Ha lictus teqularis, Sphegida'; Ammophila comlitor. Pontederia cordata L. Blue; spikR dense, from a spathe-like bract. Perianth funnel form; two-lipped, three upper divisions united to form the three-lobed upper lip; the three lower ones spreading. The upper lobe of perianth is marked by a pair of yellow spots, which aid the insect in finding the nectar. Stamens six, the three anterior long, exserted; the posterior three with very short filaments unequally rnserted lower down. Anthers versatile, oval and Llue. Pistil one, with stigma turned upwarcl. Visitor-HY)IENOPTERA-Apidae: Ha/ictus teg1thtris feeding on nectar. OBSERVATIONS ON THE POLLINATION OF SO:VIE OF TliE CO:VIPOSIT.iE. BY MAUY ALICE NICHOLS. The brilliant appearance of our western roadsides and pra1nes from .Tuly to Octobn, invites an extended study of the anatvmy and pbysiology of the Com-positre. The wide distribution and rapid increase of this family naturally call attention to dissemination and pollination. Darwin, Herman :MuellPr, and others, have shown at length, the direct relation between special adaptations for cross-pollination and the race stability of plants. The question now arises, what are the opportunitiec; for cross-pollination in Compositae, and to what extent is this agent a factor on the increase and distribution of the family? No attempt is here made to go into a discussion in full of these questions for the entire Family, but simply to present a few facts relative thereto, gathereJ from repreoentatives of the sub-tribes Heliautheae and Astel'ineae. A few obsrrv<1tions on the common cultivated sunflower, IIeli•rnthus annuu.~, will apply equally well to all member~ of this conspicuous genus. First among these may be noted the mechanism of flowering. Immediately following the 1Nichols: Observations on the Pollination of Some of the CompositaePublished by UNI ScholarWorks, 1893IOWA ACADEMY OF SCIENCES. 101 bursting of the tubular corolla, the anther tube formed by the lateral union of the five anthers and enclosing the stigma, is protruded, its entire length appearing beyond the corolla tube. The anthers now dehisce liberating the stigma which forcibly protrudes itself, at tho same time recurving and carrying with it, lodged in its. papillose projections, numerous pollen grains. The filaments then retract drawing the empty anther tube again within the corolla. Furthermore tbe disk flowers open from circumference to center. \Vere the pollen of the outer row not potent in the fertilization of its own stigma, it must be conceded to be entirely useless so far as indivitlual di,-lrn are concerned. Moreover, if tbe flowern at the center of the disk which open after the retraction of the anther tubes in the outer rows, were wholly depenclent upon cross-fertilization, we might expect to find them in many cases sterile. X o e\·idence of such a condition occurs. Hence, we con-clude from its complete mechanism and from results exh1biteu, that in the sun· flower ample provision is made for self-fertilization. But the fact that the flower is thus well equipped for its own perpetuity does not exclude the possibility of the co-operation of outside agents. The evidences of cross-fertilization by means of insects are equally numerous and conclusive. ·while the flowers around the border are opening, the center of the disk, glabrous with odorous resin, is a favorite resort for various Hymenoptera. The nectar of the flower appears to be secreted at the base of the corolla, where the style is attached. To reach the nectar it is not neces-sary that the proboscis of the insect he inserted in~ide the anther tube. Hence, it would seem at first thought quite probiJ,le that it might escape without carrying any pollen. This may in some instances be frue, but it is to be further noticed that the slightest mechanical pressure at the base of the style, before dehiscence, thrusts the stigma out with an explosive effect so that a bee entering the flower at this point would he completely ,lusted with pollen. The complete exposure of the stigmas of older flowers woukl insure the deposit of some of this pollen npon them as the bee passes over. Furthermore, the fact of the legs of the insect being sticky from the resin so a1mndant on the disk, together with the abundance of pollen produced, would afford reasonable grounch for the conclusion that pollen is thus transported. Actual observation confirms this view and it is a well known fact that flowers of this family are subject to frequent visits from both nectar and pollen gatherers. Sir John Lubbock in his "British Wild Flowers" shows the Compositro to be specially adapted for fertilization by insects from the facts that (1) the heads are conspicuous, (2) the honey easily obtained, and (8J the small size of the florets insures the touching of many by one iusect and hence effectual pollination. Hermann Mueller also recognizes this agency and notes the special modification of certain parts in the inrnct for this purpose. It is not the purpose of this paper to furnish complete lists of the insects which have been touml on the species cited, but rather to point out some of those most persistent about certain flowers ancl determine, if possible, something as to their importance in pollination. On Heliamlws a mm us L. by far the most frequent visitor was the common honey bee (Apis mellijica). This was especially true of plants growing near hives of bees, but was also true of plants obsen·ed in other localities. Bombus Penusyl-vanicus was also a frequent Yisitor. It was sometimes found with its legs heavily laden with pollen, but usually it was packed into a sort of wax. This was also true, many time~. of the honey bee, but in both cases loose pollen grains were found scattered abundantly over the head and body of the insect, in a position to be easily brushed off. Other visitors were JJfellisodes obliquus, closely resembling 2Proceedings of the Iowa Academy of Science, Vol. 1 [1893], No. 4, Art. 31https://scholarworks.uni.edu/pias/vol1/iss4/31102 IOWA ACADEMY OF SCIENCES. the bees just described, and Diabrotica longicomis, whose proboscis and antennrn were frequently found sticky with nectar or resin, to which numerous polleu grains adhered. On Helfrmthus grosse serratus Martens, a very showy species which flowers in September and forms corymb like clusters, the following wPre found: Diabrotica longicornis, Bombylini, whose downy body and barbed proboscis were admirably a•htpted for transp~rtation of pollen, and Jfonlellrslina conrnta, a small brown beetle fon ncl in great numbers buried deep in the disk both before and after the open-rng of the disk flowers. The legs and antennae are slightly downy and in some case~ adherent pollen occurs. On H. J"igidus the common visitors were Bombylini, Bombus, and A pis mell{fica. Jn addition to these, Hermann M neller gives for H. mult(flo1·ae: Megachile cent-w1cularia, Halictus zonulus, Eristalis tenax, Syrphus pyrastie, and Syrphus 1·ibesii. Un H. laetifiorus Pers. were found Bombus Pen11sylv1111icus, and Diabrotica lonqicornis. On this, as on several other members of the genus, grasshoppers fre-quPntly appeared. They werr, very destructive, to the ray flowers, but apparently played no part in the process of pollination. The g-enera Lepachys and Rudbeclcia stand so close, structurally, to Helani-thits, as to need no special description. On Lepachys pinnata Torr. and Gr., JJfellisodes obliq1ws and Phymata woljii, were found. On Rndbeckia hirta and R. triloba, the only common visitor observed was Phy-11u1ta wo(fii. Since these are abundant ancl w1clely distributed species, and since this insect is one of slow movement; and, moreover, one on which no pollen was at any time detected, it seems reasonable to conclude the species of this genus are largely self-pollinating; R. subtomentosa, however, being sweet-scented, is fre-quently visited by bees (Apis mellifica). In smaller heads, but scarcely less showy than the Helirrnthoidece, is the extensive genus Solida:JO, of the Asteroidere. The flowering mechanism of Solidngo and Heliantlrns are practically the s<tme, except that in Solidago the anther tube remains protruded for some time before oehiscence. and in the meantime the cor-olla fades. Hence the most showy period of the flower's existence occurs before the maturity of either stigma or anther. Its le,s attractive appearance is, per-haps, overbalanced by the distinct odor which :;eems intensified by the beJ:;innin~ of the process of decay. Insects were observed on the following species: Solidayo speciosa and S. lmi-ceolata. The frequent visitors were Acina11dero p1tlchella, Ammophila, and Epi-cauta pe11nsyl1)(t11ica. Of these, the last named is ~o common as to be intimately '1-;sociated with the fl0wer in the minds of the most casual observer.s. It appears usmtlly, soon after th~ deshiscence of the anther-occasionally beforn-ancl plies industriously from lbwer to flower, apparently finding nectar at the ba'e of the pistil, and industriously bra.ring pollen from floret to ftnret, and from he:i.cl to head. Ammnphilct flits very r.tpiclly. alighting- but for an instant here and there, and affording- no opportunity for observations on its motives or operations. On other species, Mueller furnishes th~ following more c)rnplete lists: On Solidayo Canadensis,-Eristnlis m·busto1·11m E. nemonun. Syritta pipiens• S11rcnphaga canrnrirt, and numerous small Jluscidae. On Solidayo virga·aurea (L.):-Ap s mellifica, Bomb11s rupestris, B. campestris, B letTestris, Andrena denti-culata, Eristalis arb11stonun, E. nemontm and Thecla ilicis. 3Nichols: Observations on the Pollination of Some of the CompositaePublished by UNI ScholarWorks, 1893row A ACADEMY OF SCIENCES. 103 TIIBLIOGRAPHY. Allen, Gnnt, "Knowledge of Snnf!owers," 1884. Asa Grav, " Notes on :\Iovements of Andrce~ium in Sunflowers," Proceedings Acacl. Nat. Sc., Phila., 1884, pp. 287·288. Th. :\feehan, ''On Elasticity in the Filaments of Helianthus," Loe. cit., p. 200. C. Schwartz, "Form of Stigmata Before and After Fertilization in Different Fam-ilies," Pringaheim 's J ahrbuch. Wiss. Botanik XV. Heft. I. Hermann )lueller, "Fertilization of Flowera." Sir John Luu bock,'' British \Vile! Flowers in Relation to Insects." ADDITIONS TO row A FLORA. PROF. B. FINK, FAYETTE, IOWA. In my collecting la-it summer about Fayette, I found the following plants, eome of which, so far as I know, have not been reported for Iowa. Those marked with a "star" have been examined by varioua botanists. The others I report on my own determination: * Habenm·in t1·i1lentctlrt, Hook. Borders of woods; rare. "'H. psycodes, Gray. \Vet river banks; rnre, new. * H. hookel"i, Torr. var. oblo11gijolia, Paine. As common as the type hera; new. Dicentra Crtnrulensis, D. C. \Voods, nue. Also reported from Decorah by E. D. W. Holway. (Proceedings Iowa Acad,1my of Sciences, Vol. I, Pt. II, p. 16.) ~ULDEWS. In this list I have acbpted the synomony given by Prof. Burrill in North Ameri-can Pyrenomycetes. SPHAEROTHffiCA Hu)IULI (DC) Burrill on Ag1·imonia Eupatol"ia. S. PANNOSA, (Wallr.) Lev. on Rosa blanda. *S. :\!ALI, (Duby.) Burrill on Pyrus Jfrtlus also reported from Ames, by Prof. L. H· Pammel and G \V. Carver abundant on young suckers, New. S. :J'Ions-1.:V.rn, (Schw.) B. ancl C. on Ribes. S. C.-1.sTAG:S-EI, I,,v. on So11chus Jleraceus. ERYSIPHE CO)D!UNIS, ( Wallr.) Fr. on Astragalus Canadensis. E. CrcHOIUCEARUM, D C on Phlo.r Drumondii. "'E. G . .i.LEOPSIDIS, DC on Sc11tellaria laterijlom, New. E. Gn.un~ns, DC on Pon pratensis. UNCI:'IULc\ CLIN l'ONII, Peck, on Tilia Ame1·icana. U. NECATOH (Schw.) Burrill en cultivated grapes (Vitis lab1·uscce). U. CIHC!NATA, C. & P., Acel" b1trbrrtwn. ~- )L\CHOSPORA, Peck, on Alnus Americana. U. S..1.Lrcrs, (0 C), on Popul11s t1·em1tloides. PHYLLACT!:SLI. SUFYULTA (Reb.) Sacc. on Camus stolonije1·, Xanthoxyl111n American nm. 4Proceedings of the Iowa Academy of Science, Vol. 1 [1893], No. 4, Art. 31https://scholarworks.uni.edu/pias/vol1/iss4/31

Observations on the Pollination of Some of the Compositae

https://scholarworks.uni.edu/cgi/viewcontent.cgi?article=7381&amp;context=pias

Observations on the Pollination of Some of the Compositae

Abstract

Similar works

Full text

Available Versions

University of Northern Iowa