Schaffner, John H.

The Ohio Journal of Science

KnowledgeBank at OSU

"The Ohio Naturalist,PUBLISHED BYThe Biological Club of the Ohio State University.Volume II, MARCH, 1902. No. 5.TABLE OF CONTENTSSCHAFFXER—On the Use of Some Common Botanical Terms 215KELLERMAN—Proposed Algological Survey of Ohio , . 219ELLIS AND KKLLKRMAX—A New Species of PhyllostictaOSP.ORX—Remarks on the Study of Leaf-IIoppersKELLEJIMAX—Poison Ivy and Ivy PoisoningIIINE—New or Little Known Dip tera * 228TYLEii-Meeting of the Biological Club 230ON THE USE OF SOME COMMON BOTANICALTERMS.JOHN H. SCHAFKNRR.The revolution which has taken place in the science of botanyduring the last fifty years has given to many of the older termsan entirely new meaning. The following explanations are offeredto indicate in a general way the proper use of some of the termswhich are continual^ recurring in the class room and which standfor definite ideas and facts as at present recognized. They willbe used by the writer until something better is proposed.In the first place, it is of the greatest importance to clearlyrecognize the alternation of generations in all of the plants abovethe Thallophytes as well as in those Algae and Fungi where atrue alternation exists. The alternation of generations lies at thebottom of the entire evolutionary history of plants and to ignorethis fact is to start with confusion as a foundation. With begin-ners one need not go into details, but so far as one does go, so farhe should tell the whole truth and leave no room for false impres-sions. It is best to speak of the two generations and the plantindividuals only as gametophyte and sporophyte and to drop suchterms as sporogonium, oophore, and oophyte when speaking ofthe individual or of the generation. The gametophyte is thesexual generation and the sporophyte is the non-sexual one. Sexterms should be used only for the sexual generation and all sexterms should be discarded when the sporophyte generation isunder discussion. It is just as easy to say carpellate flower asfemale flower, or staminate tree as male tree. In speaking of thegametophyte, if the two sexes are united in one individual the2242272i6 The Ohio Naturalist. [Vol. II, No. 5,proper terms are hermaphrodite or bisexual, and unisexual whenthe sexes are separated. Monoecious and dioecious should not beused for sexual individuals ; these terms are properly applied onlyto the sporophyte.Reproduction may come under three general heads : i. Veg-etative propagation. 2. Reproduction by non-sexual spores.3. Sexual reproduction in which spores are formed by the conju-gation of two gametes or two coenocytes. Any specialized partor branch of the gametophyte which bears the sexual organsshould be called a gametophore. The gametophores may beantheridiophores, archegoniophores, oogoniophores, etc. Theorgans which bear the male and female cells are the spermary andovary, but these may have various special names, as oogonium,archegonium, antheridium, depending upon their structure. Thesexual cells are gametes, and should be called spermatozoid andoosphere, or simply sperm and egg. Normally these two cellsmust unite to give rise to a spore. The union of the male andfemale gametes is known as fertilization. This term must neverbe used for pollination. Pollination is the transfer of a smallmale plant to an ovule or a stigma. Sexually formed spores areeither zygospores or oospores—zygospores when the uniting cellsare not at all or very little differentiated from each other, oosporeswhen they are spermatozoid and oosphere. The product ofcoenocytic conjugations may be called coenocytic zygospores, etc.The term sporophore may be used for any organ which bearssporangia, whether on the gametophyte or sporophyte. Thenthe sporophore may be a sporophyll, or otherwise. Sporophoreis a general term for a spore-bearing organ or branch. Thesporophore may be a conidiophore, a zoosporangiophore, etc.,according to the nature of the spores produced.A flower is a modified spore-bearing branch without sexualorgans. In some cases complete sterilization may have resultedso that no spores are produced. Such a flower is one, neverthe-less, which was a spore-bearing organ in the earlier stages of itsphylogeny. It is sometimes difficult to distinguish betweenspores and brood-buds, but all specialized reproductive cells shouldbe called spores. The term spike should not be used for a prima-tive flower or shortened branch of sporophylls. Such flowersmay be called cones—as cone of Equisetum, Iyycopod, Pine, etc.The spike is an inflorescence. The flower may be either mono-sporangiate or bisporangiate. If it is monosporangiate it may bemonoecious or dioecious. These terms should be applied only toheterosporous sporophytes. Monosporangiate flowers are eithermicrosporangiate or megasporangiate. In the case of Spermato-phytes they may be called staminate and carpellate. Suchexpressions as hermaphrodite flowers, and polygamous flowersMarch, 1902.] Use of Some Common Botanical Terms. 217are al together misleading. T h e typical flower is made up of foursets of floral organs, as follows :-p, ., | 1. Gynoecium—composed of carpels.Pc ( 2. Androecium—composed of stamens.CA. ••• , f T,. Corolla—composed of petals.Sterile parts.. . < ° ~ , F Fr (4. Calyx—composed or sepals.Gynoecium and androecium should simpl}- mean the house orplace in which the male and female plants live and thus the mis-take will be avoided of implying sexuality to the carpels andstamens. The term sterile should never be applied to a staminateflower. It is manifestly absurd to continue to call a staminateflower sterile when it produces a large number of microspores.A sterile flower is one which has lost the power of spore repro-duction. The term pistil is very misleading and should not beused except for a gynoecium in which the carpels are completelyunited. It would be better to not use it at all. The parts of anycycle or whorl of the flower may be free or partly united or com-pletely united and these conditions can be easily indicated withouta special terminology. The older terms in regard to the sym-metry of the flower should be completely dropped and the newerones, which accord with mathematical conceptions, be used.According to Barnes, stigma, style, and ovulary are the usualparts of a carpel. Ovary should only be used for an egg-produc-ing organ of the gametophyte. If the carpels are free the ovular-ies are simple ; but for convenience, if the ovularies of a numberof carpels are united the entire structure may be called a com-pound ovulary with so many loculi or cavities. The term cell isto be used only in its cytological sense as the unit of plant struc-ture. To speak of the cells of the ovulary or of the stamen wrhenthe loculi are meant is misleading.The ovule is originally the megasporangium and produces oneor more megaspores. The microsporangia are borne on the stamensand produce the microspores. The pollen grain and the embryo-sac are the male and female plants of the gametophyte generationof the seed plants, and develop from the microspore and mega-spore, respectively. A distinction must be made between themicrospore, which is a single cell, and the polleugrain, a several-celled male gametophyte ; also betwreen the megaspore, a singlecell, and embryo-sac, the female gametophyte. The pollentubeis not the male gametophyte, but only a part of that individual.The entire structure, wThich develops from the microspore, is themale gametophyte. The pollengrains should not be called pol-lenspores, nor should the embryo-sac be called a megaspore.Endosperm should be restricted to the Angiosperms and stand forthe tissue or cells which come from the definitive cell, and in such218 The Ohio Naturalist. [Vol. II, No. 5,cases as the Pine the tissue which surrounds the embryo can becalled what it actually is, the female thallus or female gametophytefilled with food material.The term root must be restricted to the sporophyte generationand root-hairs to hairs on real roots. The terms rhizoid and hold-fast may be used for similar organs of the gametophyte. Theword leaf should be restricted entirely to the sporopyte. Anyreduced leaf may be called a bract or scale-leaf. For expansionson the gametophyte the term scale may be used as moss scale,liverwort scale, scaly Liverworts, etc. Expanded thalli, as thosein many of the red and brown Algae, and Liverworts and Mossesmay be called fronds. There is no need of calling a fern leaf afrond. It is of the same nature as the leaf of a seed plant and.should have the same terminology. The term stoma should beused only for true stomata on the sporophyte. Passages of some-what similar function, but not similar structure on the gameto-phyte of some Liverworts may be called air passages for want ofa better term. It would be well to drop the term prothallus inthe Pteridophytes and call the gametophyte, what it really is,simply a thallus. The term germinate should be restricted tothe division or budding of cells and spores; it should not be usedfor the breaking out of the embryo plant from the seed. Thisprocess should always be called sprouting. There is not even ananalogy between this process and the germination of the spore.The terms photosynthesis, digestion, respiration, and assimila-tion should be properly applied, especially assimilation, whichshould refer only to the conversion of dead food materials intoliving protoplasm. It would be very fortunate if the termsdaughter cell, mother cell, and grandmother cell would always beapplied to successive generations of cells produced by division.Thus in the formation of the spores on the sporophyte, the cellswhich are differentiated and usually separated from the generaltissue are spore grandmother cells. These divide into two toform the two spore mother cells, which again divide, thus form-ing the four daughter cells which develop into the spores. Thesegrandmother cells are usually called spore mother cells, but it isbetter to use the term sporocyte, and if there are two kinds ofspores, the cells may be called microsporocytes and mega-sporocytes.These are only a few of the most important terms that mightbe defined, but if these alone were always correctly applied,amateur students as well as those more advanced might obtain aclearer conception of the subject with much less outlay of misdi-rected effort.

On the Use of Some Common Botanical Terms

https://kb.osu.edu/bitstream/1811/1271/1/V02N05_215.pdf

On the Use of Some Common Botanical Terms

Abstract

Similar works

Full text

Available Versions

KnowledgeBank at OSU