Native North American Species Research Articles

Use of Plant Introductions in Peanut Cultivar Development

Abstract The genetic base of peanut (Arachis hypogaea L.) in the U.S.A. has at times been extremely narrow, particularly in specific production areas where a single cultivar may be grown in near-monoculture. Because peanut is not a native North American species, all U.S. cultivars necessarily trace their ancestry to plant introductions (PIs), but most of the genetic base of current cultivars rests on selections from farmer-stock peanuts of obscure origin. The objectives of this study were to (a) summarize and document the use of introduced genetic resources in cultivar development and (b) estimate the resulting economic impact. Different PIs were used as parents in early breeding programs. B.B. Higgins used Gambian line Basse as a parent of the GA 207 cross that gave rise to selections used in Georgia, Florida, and North Carolina as the basis for further improvement. PI 121067 was one of seven parents used by W.C. Gregory to initiate the program in North Carolina. A different set of PIs including PI 121070, PI 161317, PI 168661, and A. monticola Krapov. & Rigoni were used in the Texas and Oklahoma programs. Recycling of lines as parents and exchange of germplasm among breeding programs proliferated these PIs in the pedigrees of cultivars released since 1960. Over the past 20 yr, there have been concerted efforts to incorporate additional germplasm into U.S. breeding populations, usually with the purpose of improving resistance to diseases or pests, but also with the objective of broadening the genetic base. These efforts have had a significant economic impact on U.S. peanut farmers, the largest from the development of cultivars with resistance to Sclerotinia blight (Sclerotinia minor Jagger), root-knot nematodes (Meloidogyne spp.), and tomato spotted wilt virus. Use of these resistant cultivars has an economic impact of more than $200 million annually for U.S. peanut producers. In the runner and virginia market types, the average PI ancestry of all cultivars was 17.9%. There are several examples of successful cultivars with up to 25% ancestry from a single PI, including Georgia Green and NC-V11. In the spanish market type, most successful cultivars have derived 50% or more of their ancestry from PIs. Several recent or impending releases incorporate PI germplasm but have not yet been proven in the U.S. seed market.

Invaders Today, Natives Tomorrow?

Models of colonizing species and episodes from the annals of population biology tell us that colonists, including exotic species or potential “biological invaders” (“Biological Invaders,” 17 Sept., p. [1834][1]), are most vulnerable to local extinctions early in an invasion. Once a colonizing species gains considerable momentum in staking its evolutionary claim on a habitat or ecosystem, it becomes all but invincible. Therefore, it seems to me that it makes little sense to attempt to control well-established biological invaders (foreign colonists) with equally exotic control agents. Only in the earliest stages of a biological invader's population growth cycle would eradication be possible, but unfortunately this is the most cryptic phase of the colonizing strategy, making detection of a potential problem extremely difficult in many cases. I advocate the notion that the entire planet is, and has been, one mammoth mixed-bag of countless colonizing episodes, both in geological and in contemporary time. We are focusing a lot of attention on the invasions of species within very small scales of time, but Earth's intermingling of organisms from different continents and seas has been occurring for millions of years. Doesn't it therefore follow that in cases today where biological invaders have strong footholds, that they are best left alone? Isn't it possible that at some point these populations will be naturally controlled by new interrelationships with local species and climate? In other words, at some point biological invaders have the potential of becoming new or quasi-native species. # {#article-title-2} Investigations of biological invaders may be more complicated than it would first appear. For many potentially noxious pests, we do not have adequate information about their native distribution. For example, concern was raised in the 1980s when Bursaphelenchus xylophilus , a parasitic nematode that severely damages native pines in Japan, was found to be responsible for the rapid death of mature pine trees in the midwestern United States ([1][2]). Concern lessened, however, when it was determined that it was primarily exotic, non-native pines that were dying and that the nematode was probably a North American native species. Similarly, the soybean cyst nematode, Heterodera glycines , was first observed in North America in North Carolina in 1954. Records suggested that the nematode was introduced with shipments of tulips from Japan ([2][3]). In spite of quarantines, the nematode spread to every soybean-producing state and, in 1997, it was estimated to have reduced U.S. soybean production by 218 million bushels ([3][4]). Its rapid spread has led some researchers to suggest that the nematode may have been endemic to North America, existing on related weed hosts, and that its distribution expanded with increased soybean production. Another theory has implicated importation of soil from Japan in the late 1800s to obtain Bradyrhizobium japonicum for soybean root nodulation. Biotic surveys and inventories of native organisms are critical for the proper identification of biological invaders. 1. [↵][5]1. V. H. Dropkin 2. et al. , Plant Dis. 65, 1022 (1982). [OpenUrl][6] 2. [↵][7]1. N. N. Winstead 2. et al. , Plant Dis. Rep. 39, 9 (1955). [OpenUrl][8] 3. [↵][9]North Central Region-137 subcommittee on soybean disease losses, report on loss estimates for the U.S. 1996–1998 available at . [1]: /lookup/doi/10.1126/science.285.5435.1834 [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #xref-ref-1-1 View reference 1 in text [6]: {openurl}?query=rft.jtitle%253DPlant%2BDis.%26rft.volume%253D65%26rft.spage%253D1022%26rft.atitle%253DPLANT%2BDIS%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [7]: #xref-ref-2-1 View reference 2 in text [8]: {openurl}?query=rft.jtitle%253DPlant%2BDis.%2BRep.%26rft.volume%253D39%26rft.spage%253D9%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [9]: #xref-ref-3-1 View reference 3 in text

Relative Susceptibility of Peach and Plum Germplasm to Armillaria Root Rot

Nearly 5000 seedling trees representing more than 100 peach [Prunus persica (L.) Batsch.] and plum (Prunus spp.) lines were planted at a 4 × 0.6-m spacing in Jan. 1983, on a site with a known history of peach tree short life (PTSL) and Armillaria root rot (ARR). Trees were arranged in a randomized complete-block with eight replicates of six trees each. Beginning in Spring 1984 and each year thereafter the cause of tree death was determined. At the end of 9 years, 50% of the trees had succumbed to PTSL and 35% had been killed by ARR apparently caused by Armillaria tabescens. Analysis of the data for trees killed by ARR showed a wide range in mortality, some peach lines appeared significantly more tolerant to ARR than others. Plum lines derived from native North American species also appeared to be a potential source of improved tolerance. We did not establish whether ARR tolerance is affected by PTSL.

Water Absorption and Contact Angle Measurement of Native European, North American and Tropical Wood Species to Predict Gluing Properties

In order to optimize the gluing performance of wood splints with KPVAC-glues, it is of utmost importance to know the amount of water able to penetrate into the gluable wood splints. Therefore, in this study two techniques to measure the water absorption ability of building materials were applied on a variety of 40 representative tropical and native European wood species. The first method is a common German standard and measures the water absorption coefficient w t . The second is based on the determination of the wettability of surfaces by measuring equilibrium contact angles of liquid water. Using a similar technique, we have concentrated our research on the dynamics (non-equilibrium) of a water drop contact angle. Differences among species are outlined and discussed primarily with respect to wood extractives contents and wood densities. Even though it must be assumed that both techniques are based on equal mathematical relations, a poor correlation was obtained.

New Combinations in Asian Krascheninnikovia Gueldenstaedt (Chenopodiaceae)

New combinations in the genus Krascheninnikovia are proposed: K. arborescens (Losina-Losinskaja) Mosyakin, K. compacta (LosinaLosinskaja) Grubov var. longipilosa (Tsien Cho-po & Ma Cheng-gung) Mosyakin, and Krascheninnikovia sect. Caudatae (Aellen) Mosyakin. Krascheninnikovia Gueldenstaedt (1772: 551) is the correct name for the genus previously commonly known as Eurotia Adanson and Ceratoides Gagnebin. This nomenclatural problem has been discussed by several authors over the years (LozinaLozinskaya, 1930; Reveal & Holmgren, 1972; Grubov, 1976; Guterman, 1975; Tomsovic, 1990; Tsvelev, 1993). Unfortunately, when establishing the genus Ceratoides, Gagnebin (1755: 59) did not write a diagnosis, but rather only mentioned a pre-Linnaean work by Tournefort (1703). In the latter work the genus Ceratoides included both an annual species (later named by Linnaeus as Ceratocarpus arenarius L.), and a perennial one, which is conspecific with Krascheninnikovia ceratoides (L.) Gueldenstaedt. At the time of its establishment (Gagnebin, 1755) the genus Ceratoides included Ceratocarpus arenarius, the type of Ceratocarpus L. (1753); thus Ceratoides is a synonym of Ceratocarpus. The next available name for the genus is Krascheninnikovia. [More detailed discussion is provided by Guterman (1975) and Tsvelev (1993).] In the Flora Reipublicae Popularis Sinicae (Tsien Cho-po & Ma Chenggung, 1979) the name Ceratoides was accepted for this genus. Thus, the following new nomenclatural combinations are necessary for a forthcoming edition of the Flora of China. Krascheninnikovia arborescens (Losina-Losinskaja) Mosyakin, comb. nov. Basionym: Eurotia arborescens Losina-Losinskaja, Izv. Akad. Nauk SSSR, Ser. 7, Otd. Fiz.-Mat. Nauk 1930, No. 9: 999. 1930. Ceratoides arborescens (Losina-Losinskaja) Tsien Cho-po & Ma Chenggung, Flora Reipublicae Popularis Sinicae 25(2): 27. 1979. Krascheninnikovia compacta (Losina-Losinskaja) Grubov var. longipilosa (Tsien Cho-po & Ma Cheng-gung) Mosyakin, comb. nov. Basionym: Ceratoides compacta (Losina-Losinskaja) Tsien Cho-po & Ma Cheng-gung var. longipilosa Tsien Cho-po & Ma Cheng-gung, Flora Reipublicae Popularis Sinicae 25(2): 28. 1979. When first describing the new variety Ceratoides compacta (Losina-Losinskaja) Tsien Cho-po & Ma Cheng-gung var. longipilosa Tsieng Cho-po & Ma Cheng-gung, the authors did not cite the basionym for their new combination at the species level (see Kung Hsien-wu et al., 1978). Thus, the complete combination (species plus variety) was validated later n the Flora Reipublicae Popularis Sinicae (Tsien Cho-po & Ma Cheng-gung, 1979). Two sections, based mostly on the differences in the structure of trichomes, were established by Aellen (1952) for the genus Eurotia. The correct names for these sections, as well as a new combination for one of them, are given below. Krascheninnikovia sect. Krascheninnikovia. TYPE: Krascheninnikovia ceratoides (L.) Gueldenstaedt (type of the genus). Eurotia sect. Ecaudatae Aellen, Verh. Naturf. Ges. Basel 63: 267. 1952. TYPE: not designated. Because in Aellen's (1952) treatment the section Ecaudatae included the type of the genus, this name should be replaced by the appropriate autonym. Krascheninnikovia sect. Caudatae (Aellen) Mosyakin, comb. nov. Basionym: Eurotia sect. Caudatae Aellen, Verh. Naturf. Ges. Basel 63: 267. 1952. TYPE: Eurotia compacta LosinaLosinskaja = Krascheninnikovia compacta (Losina-Losinskaja) Grubov. The native North American species previously commonly known as Eurotia lanata (Pursh) Moquin-Tandon was transferred to Krascheninnikovia by Meeuse & Smith (1974). If accepted as a distinct NovoN 5: 52-53. 1995. This content downloaded from 157.55.39.34 on Fri, 13 Jan 2017 18:16:50 UTC All use subject to http://about.jstor.org/terms Volume 5, Number 1 Mosyakin 53 1995 Asian Krascheninnikovia entity, another North American taxon described by Rydberg (1912) as Eurotia subspinosa is in need of the same transfer or a new infraspecific combination. However, in view of the current work on the Flora of North America project, I believe this nomenclatural decision should be left to American

Taxonomic implications of SDS-PAGE analyses of seed proteins in North American taxa of Festuca subgenus Festuca (Poaceae)

The banding patterns of seed storage proteins generated by sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of extracts of seed of North American native species of Festuca subgenus Festuca produced taxonomically useful characters. The results support (1) treating F. dasyclada Hackel ex. Beal as a Festuca and placing it in subgenus Festuca, (2) recognizing F. brachyphylla Schultes, F. idahoensis Elmer, and F. saximontana Rydb. as full species and (3) recognizing F. rubra ssp. densiuscula (Hackel) Piper and F. rubra ssp. richardsonii (Hooker) Hultén as subspecies. Limited evidence suggested that the seed protein profile of F. baffinensis differs from F. brachyphylla. Distinct height forms in adjacent plants of F. brachyphylla and F. idahoensis have almost identical seed protein banding profiles and on these criteria do not justify recognition as taxonomic entities. A Californian sample of F. saximontana var. purpusiana (St.-Yves) Frederiksen and Pavlick has a seed protein profile distinct from samples of F. saximontana var. saximontana, suggesting the variety name should be limited to endemic populations near the type locality in California and not applied to mere height forms in other areas. Variation in F. brachyphylla profiles may reflect (1) geographic isolation in populations and independent evolution of seed proteins, possibly as a result of founder effects, (2) isolating mechanisms such as differences in flowering time, or (3) introgression following hybridization with other taxa.

An Intergeneric Hybrid of a Native Minnow, the Golden Shiner, and an Exotic Minnow, the Rudd

The hybrid golden shiner Notemigonus crysoleucas × rudd Scardinius erythrophthalmus is the first known nonsalmonid, intergeneric hybrid of an exotic species and a North American native species. The cross is also the first valid record of a viable hybrid involving the native golden shiner. Meristic and mensural characters of 30 artificially produced hybrids of male golden shiners and female rudds were analyzed. Forty-seven percent of the meristic traits exhibited character states intermediate between those of parents. Twenty-seven percent of the meristic characters were supernumerary, suggesting developmental instability of the hybrid genome. Mensural hybrid characters were significantly skewed to the golden shiner phenotype. The skewed mensural inheritance and other skewed patterns of morphological inheritance also suggest problems in canalization of the hybrid phenome or atypical patterns of dominance. All hybrids were identifiable by intermediate squamation of the cultrate abdomen: the keel was mostly scaled but exhibited a small fleshy ridge posteriorly. This minnow hybrid allows general inferences to be made about the phylogenetic affinity of the golden shiner to other cultrate cyprinids of Eurasia. The hybrid cross has important management and conservation implications for fishes in North America. The hybrid is an example of how an exotic species may negatively affect a native species.

SDS–PAGE of seed proteins in Festuca (Poaceae): taxonomic implications

Taxonomically useful descriptors were provided by the banding patterns of seed storage proteins obtained when extracts of bulked, ungerminated seed samples from commercially available North American native species of Festuca were analyzed by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS–PAGE). The banding patterns for three species of rough fescues (section Breviaristatae Krivot) indicate that although the taxa are closely related, F. campestris Rydb. (2n = 56) does not appear to be an autoploid of either F. altaica Trin. (2n = 28) or F. hallii (Vasey) Piper (2n = 28). A distinct band corresponding to a molecular weight of 57 000 occurred in the seed protein profiles of all native and commercial samples of Festuca L. analyzed. The profile for F. californica Vasey, questionably section Breviaristatae, also has a band at this position, and is very different from that of F. altaica, F. campestris, and F. hallii. Species-specific banding patterns were observed for F. brachyphylla Schultes, F. saximontana Rydb., F. idahoensis Elmer, and F. trachyphylla (Hackel) Krajina (F. ovina L. s.l., F. longifolia Thuill., F. ovina var. duriuscula auct. amer.). The results support the recognition of subgenus Schedonorus (Beauv.) Peter., and sections Breviaristatae Krivot and Festuca. Key words: Poaceae, Festuca, SDS–PAGE seed proteins.

Natural intersectional hybridization between North American species of Populus (Salicaceae) in sections Aigeiros and Tacamahaca. II. Taxonomy

Five of six possible hybrid combinations of the two native North American species of Populus sect. Aigeiros Duby with the three native species of sect. Tacamahaca Spach have been found in nature. Putative hybrids occur wherever species of the two sections are sympatric and sometimes even beyond the range of one or both parents. Parents of the sixth possible combination are not, however, sympatric and this explains the apparent absence of the corresponding hybrid. Although the five hybrids can easily be recognized as a group, each parentage yields hybrids of unique morphology, all of which have previously been provided with binomials. Variability within each hybrid reflects variation in its parents. These hybrids are morphologically intermediate between their putative parents and have an additive chromatographic profile combining leaf flavonoids of each pair. Trees of P. × generosa (P. deltoides × P. trichocarpa) and P. × jackii (P. deltoides × P. balsamifera) from natural populations closely resemble artificial hybrids between their presumed parents. Three natural hybrids, P. × acuminata (P. deltoides × P. anguslifolia), P. × jackii, and P. × parryi (P. fremontii × P. trichocarpa), are all cultivated as shade trees. Keys distinguish the five hybrids from each other and from their parents; each hybrid is described; its nomenclature is clarified; and its range is mapped in relation to those of its parents.

Screening Prosopis (mesquite) for cold tolerance.

Cold tolerance and biomass estimation of Prosopis species were examined under field conditions. Prosopis africana and P. pallida tolerated several minus 1.5/sup 0/C freezes but none survived a minus 5/sup 0/C freeze. P. alba, P. articulata, P. chilensis, P. nigra, and P. tamarugo tolerated several minus 5/sup 0/C freezes but not a 12-hour below 0/sup 0/C freeze. Most North American native species P. glandulosa var. glandulosa, P. glandulosa var. torreyana, and P. velutina tolerated the 12 hour freeze with only moderate damage. In general trees with greater productivity belonged to the most cold sensitive accessions but sufficient variability exists to substantially improve Prosopis biomass production on the coldest areas where it now naturally occurs.

THE ORIGIN OF AMMANNIA × COCCINEA ROTTBOELL

SummaryThe wide‐ranging, native North American species Ammannia × coccinea Rottboell (Lythraceae) is determined, on the basis of morphological and cytological evidence, to be an amphidiploid derivative (n=33) of A. auriculata Willdenow (n= 16) and A. robusta Heer & Regel (n = 17). The latter species has not been recognized in modern floras but its specific status is supported by a unique combination of floral and vegetative characters and distinctive chromosome number. Artificial backcrosses produced vigorous, but pollen‐sterile F1's confirming the suggested relationship of the species. Geographical distribution of the complex is presented.

A Bibliography of North American Cherry Fruit Flies (Diptera: Tephritidae)

Cherry fruit flies (cherry maggots) are by far the most destructive pests of cultivated cherries in the world. The damage caused by these insects is very serious, and because of almost zero population tolerance, enormous amounts of pesticides are used to obtain acceptable fruit. Four species of fruit flies are known to cause significant damage to cultivated cherries. These are the European cherry fruit fly, Rhagoletis cerasi L., the black cherry fruit fly, Rhagoletis fausta (Osten Sacken), the cherry fruit fly, Rhagoletis cingulata (Loew), and the western cherry fruit fly, Rhagoletis indifferens Curran. Of these, the latter three are native North American species (Bush 1966, AliNiazee 1973). The western cherry fruit fly is distributed in west coast areas from California to British Columbia and in parts of Idaho, Montana, Utah, and Colorado. The cherry fruit fly R. cingulata is distributed in the eastern half of North America, east of Iowa. The black cherry fruit fly, R. fausta occurs in both eastern and western North America, but it is significantly less important on cultivated cherries than the other two species. The European cherry fruit fly is native to Europe. It was introduced to this country many times, but never became established in North America.

Chromosome numbers of some North American Arctic and Boreal Salix

Chromosome numbers are reported for 12 native North American species of Salix and one natural hybrid. The arctic species Salix alaxensis var. alaxensis, S. fuscescens, S. ovalifolia var. ovalifolia, S. phlebophylla, and S. reticulata and the boreal species S. arbusculoides are diploids, 2n = 38. Tetraploid counts, 2n = 76, are reported for the arctic S. planifolia ssp. pulchra. Taxa with more than one chromosome number include S. planifolia ssp. planifolia and S. pedicellaris, each of which has tetraploid and triploid levels; S. arctica s.l., which is tetraploid in the eastern American arctic and hexaploid in the Alaska and Eurasian arctic; and S. athabascensis with triploid, tetraploid, and hexaploid levels. Intra-population variation in chromosome number is reported for S. glauca in which tetraploids, pentaploids, and hexaploids occur in a single Alaskan population.

Chromosome Numbers of Some North American Salix

Chromosome numbers are reported for 19 species of North AmericanSalix, one natural hybrid, and one introduced species. The following 17 species are here examined cytologically for the first time:Salix amygdaloides Anderss.,S. arbusculoides Anderss.,S. brachycarpa Nutt.,S. Candida Willd.,S. discolor Muhl.,S. exigua Nutt.,S. kumilis Marsh.,S. interior Rowlee,S. lutea Nutt.,S. maccalliana Rowlee,S. monticola Rydb.,S. myrtillifolia Anderss.,S. pellita Anderss.,S. petiolaris J. E. Sm,S. scouleriana Barr.,S. silicicola Raup, andS. subcoerulea Piper. Of the 19 native North American species 11 are diploid, four are tetraploid, one is triploid, one hexaploid, one dodecaploid, and one exhibits more than one ploidal level.

Identification of Cyprinid Fish Reported from Kansas as Squalius elongatus

Among the most puzzling records of freshwater fishes from eastern North America is that of Squalius elongatus from Kansas (Hay, 1887: 249). Suspecting that the record was based either on a misidentification or on an intergeneric hybrid, rather than on an example of Clinostomus elongatus (Kirtland), we have not included Kansas in the range of the species (Hubbs and Lagler, 1941: 56; 1947: 64). Since, however, this dace has a markedly localized and disjunct distribution, especially toward the west, and since several northern types range or once ranged southward as far as the Missouri River system in Kansas, the record, though from a stream far removed from others known to be occupied by the species, has not totally lacked plausibility. W. Ralph Taylor on examining the specimen in 1949 determined that it has the pharyngeal teeth alignable in 3 rows, as in most Old-World cyprinids but as in no native North American species. Since this observation accentuated the enigma, I studied the specimen (U.S.N.M. 38233) critically, with the cooperation of Leonard P. Schultz, on January 13, 1951. It was reported by Hay (I.c.) as having been collected by him in the North Fork of Solomon River at Lenora, Kansas, in July, 1885.

POPULATIONS OF LINARIA ON THE GULF COAST

ABOUT PENSACOLA, Florida, occur all three of our native North American species of Linaria (Pennell, 1935, maps 82-84). These are: L. texana Scheele, which is widespread west of the Mississippi River but eastward is confined to the southern states; L. canadensis (L.) Dumort, common eastward, especially on the Atlantic Coastal Plain, and of scattered occurrence west of the Mississippi River; and L. floridana Chapman, of peninsular Florida and the Gulf Coast, with one record from the interior of Georgia. In April, 1941, the writer made mass collections of Linaria about Pensacola and at points inland as far as Atlanta, Georgia. The procedure consisted simply of taking mnany individuals from each patch of Linaria; a number of whole plants were taken and these were supplemented with inflorescences from many additional plants. If a patch had less than fifty individuals, each individual was ordinarily sampled; in very large colonies about fifty individuals were taken at random. It was found that any patch may consist of one species, or of two species, or of all three species intermixed. Table 1 shows the number of individuals of each species collected in each patch. The stations are arranged in order of distance from the Gulf of Mexico.2 ECOLOGY.-Soil requirements of the three species appear to be identical. About Pensacola, any patch of recently disturbed sand may have any or all species. Anderson (1933) observes that Iris versicolor and I. virginica, which appear to have entered the 1 Received for publication January 23, 1942. 2 For collections 1-6, distances are measured from the open water of the Gulf of Mexico on the south shore of Santa Rosa Island, and are computed from the chart of Pensacola Bay & Approaches, U. S. Coast & Geodetic Survey. The mileages for collections 7 and 8 are based on distances measured by automobile from Pensacola northward on U. S. Highway 29. Distances for collections 9 and 10 are measured on a Rand McNally map. southern peninsula of Michigan at different times, very rarely grow together. There is apparently no such exclusion of one species by another in the colonies of Linaria. Two species sometimes occupy the same habitat, but one is more limited than the other. Such a pair is Phyllitis Scolopendrium and Polystichum Lonchitis as they occur in Bruce Peninsula, Ontario. Where the Phyllitis is found the Polystichum is commonly found also, but the converse is not true, for the Polystichum is frequently found not accompanied by the Phyllitis. It would seem that the occurrence of the Polystichum is limited by a certain set of factors, and that of the Phyyllitis by the same set of factors plus others. The ranges of these two ferns are consistent with this hypothesis, for Polystichum Lonchitis, while somewhat local, is widespread in North America (Fernald, 1935, p. 207), but the American phase of Phyllitis Scolopendrium is known from but four small areas (Fernald, 1935, p. 200). This case is cited only to serve as a contrast with the Linaria situation. L. floridana is found, in this part of its retricted range, only along the Gulf of Mexico, and is quite absent from all collections not taken close to the coast. Yet where it does occur it outnumbers the two more widespread and presumably more aggressive species. Why does it fail to spread inland (except for the single inland collection recorded by Pennell, l.c.) ? There must be some factor, favorable to L. floridana and operative only along the coast (possibly climatic?), to which the other two species are indifferent. TAXONoMY.-These are three distinct species. All the specimens examined for table 1 had flowers or mature fruits, and most of them had both. There was no question of the specific identity of any individual. And yet L. canadensis shows many identical characters, on the one hand with L. texana, and on the Md.a 11:hPr wth r ;r'nn*in it. anVa IniTT rYrot