These “Floristische Notities” contain notes on the phanerogamic flora of the Netherlands. In this first series are mentioned: 1. Tetragonia tetragonoides (Pall.) O.Ktze., found in waste places, on rubbish-heaps, and also on the beach in a few localities in the province of Zeeland. 2. A specimen of Ranunculus ficaria L. with flowers composed of 3 sepals, c. 30 yellow petals and instead of the stamens and pistils c. 30 minute green leaves. 3. Nasturtium microphyllum Boenningh. ex Rchb. and N. officinale (L.) R.Br. Differences between these two species are given (see fig. 1) and the distribution in the Netherlands of the latter is discussed (see map, fig. 2). 4. Silene sericea All. Most probably casually introduced from Corsica. 5. Prunus spinosa L. f. coaetanea (Wimm. et Grab.) Schneid. Found in several localities in the Netherlands. 6. Malva sylvestris L. var. parvifolia Schur and var. purpurascens Weston. Both varieties introduced and probably also native. 7 and 12. Bupleurum semicompositum L. and Linaria triphylla (L.) Mill. Introduced near a granary at Grave (prov. of N. Brabant). 8 and 9. Angelica sylvestris L. f. nidus (Kittel) Thell. and Peucedanum palustre (L.) Moench f. involucratum Cariot et St. Lager. New records for the Netherlands. 10 and 11. Erica scoparia L. and E. ciliaris L. Both species probably unintentionally introduced during World-War II in the island of Terschelling, and at least the former becoming naturalized there. 13. Centaurium spicatum (L.) Fritsch. Found as an alien near the railway station at Leyden. 14. Artemisia stelleriana Bess. Cultivated and run wild in the dunes of the island of Voorne. 15. Leontodon autumnalis L. f. concolor (Korn.). New record for the Netherlands. 16. Schkuhria pinnata (Lamk.) O. Ktze., var. pinnata and var. abrotanoides (Roth) Cabrera. Differences between these two aliens (see fig. 3), and a list of localities are given. 17. ‘ Sagittaria latifolia Willd. Naturalized in at least one locality (a ditch near Brummen, prov. of Gelderland); also found near The Hague in a wet, shallow dune valley (fig. 4). 18. A list of ornamental plants, escaped from cultivation, of which Cornus alba L. is naturalized in a few localities.