. Atlas of the rare vascular plants of Ontario. Rare plants; Botany. HABITAT: Shallow water of lakes and ponds with sandy to peaty substrata. STATUS: Rare in Canada. Possibly extirpated in Ohio; endangered in Missouri; rare in Alabama, Indiana, Kentucky, Maryland, and Vermont. NOTES: Najas gracillima is apparently intolerant of pollution and has become increasingly rare in some areas due to the gradual degradation of lakes and streams (Wentz & Stuckey 1971). Young plants of the European species N. minor All. do not usually demonstrate the strongly recurved leaves characteristic of mature p
. Atlas of the rare vascular plants of Ontario. Rare plants; Botany. HABITAT: Shallow water of lakes and ponds with sandy to peaty substrata. STATUS: Rare in Canada. Possibly extirpated in Ohio; endangered in Missouri; rare in Alabama, Indiana, Kentucky, Maryland, and Vermont. NOTES: Najas gracillima is apparently intolerant of pollution and has become increasingly rare in some areas due to the gradual degradation of lakes and streams (Wentz & Stuckey 1971). Young plants of the European species N. minor All. do not usually demonstrate the strongly recurved leaves characteristic of mature plants, and are vegetatively quite similar to, and have been misidentified as, N. gracillima. Fruiting specimens of both species, however, are very distinctive. The style on fruits of N. gracillima arises off-center at the apex of the gynoecial wall and the fusiform seeds have areolae that are longer than broad. The slightly recurved seeds of N. minor have areolae that are broader than long and arranged in a ladder-like fashion. Because of the importance of the seeds for the identification of Najas, care should be taken to collect seed-bearing specimens. HABITAT: Eau peu profonde des lacs et des étangs à substrat sablonneux ou tourbeux. SITUATION: Rare au Canada. Peut-être déracinée dans l'Ohio; menacée d'extinction au Missouri; rare en Alabama, en Indiana, au Kentucky, au Maryland et au Vermont. REMARQUES: Najas gracillima semble vulnérable à la pollution et devient de plus en plus rare dans certaines régions à cause de la dégradation graduelle des lacs et des cours d'eau (Wentz & Stuckey 1971). Les jeunes plants de l'espèce européenne N. minor All. ne présentent généralement pas les feuilles fortement incurvées caractéristiques des plantes matures, mais leur appareil végétatif très semblable à celui de N. gracillima fait que les deux espèces sont souvent confondues. Les spécimens fructifères des deux espÃ
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectbotany
