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Cruciferae.
Cardamine pratensis Linn. Originally recorded from Whangarei by Allan (1940: 67), I have found specimens in the Plant Research Bureau Herbarium (17295) collected from New Plymouth about the same time as the original collection from Whangarei, these having been omitted in making the record. The species has been found to be established in damp places along the Waihou River, near Matatoki 45938, and near the head of the Te Awaiti drainage canal 45939, both localities in the Hauraki Plains district.
Lepidium sp. The species of this genus are difficult of determination, and the species naturalized in New Zealand have yet to be critically examined. To the present, eight species have been recorded for New Zealand, but the correct identity of certain of these is doubtful. This study has not produced a very clear picture of the naturalized species, due to the close relationships of the species as treated by Thellung in his monograph of the genus, and the lack of authentically named specimens for comparison purposes. The individual species are treated below.
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L. bonariense Linn. Recorded by Allan (1935: 4) for Wellington, this plant is not uncommon on gravel ballast along the railway line between Wellington and the Summit, Rimutaka Range.
L. campestre (Linn.) R. Br. Recorded by Thomson (1875: 372) from Otago. This species is correctly determined and the distribution is as given in local floras.
L. draba Linn. Recorded by Smith (1904: 225) from Ashburton County. This species is correctly determined and the distribution is as given in local floras; it is thoroughly established in parts of Canterbury and Marlborough.
L. heterophyllum (D.C.) Benth. Recorded by Kirk (1878a: 414) from Bendigo, Otago, as L. smithii Hook. This species has been confused with L. campestre (Linn.) R. Br., and it must be regarded as very uncommon to rare; I have seen only one specimen from the Canterbury district.
L. neglectum Thell. Recorded from Central Otago by Allan (1940: 62). I have examined these specimens, and consider them to be more correctly placed under L. densiflorum Schrad. Working with Thellung's descriptions, there appears little difference between the two species, and this suggests that Thellung's species is identical with one of the varieties of L. densiflorum Schrad.
L. ruderale Linn. Recorded by Kirk in Hooker's list of naturalized species (1867: 758), the plant to which the name was applied is widely distributed. Examination of specimens under this name in the Plant Research Bureau Herbarium indicated that these plants did not match the description of the species given by Thellung (1906: 135–39) in his monograph on the genus Lepidium. These specimens have, without exception, four rudimentary petals, varying from one-eighth to one-half the length of the sepals, four glands (“Honigdrüsen” of Thellung) about one-tenth the length of the sepals, and sepals broadly oblong, usually a dark purplish colour with long hairs on the outer surface.
In his description of the typical variety of L. ruderale Linn., Thellung (1906: 137) states “…petala nulla…” and of a Siberian variety “…(in var. intercedente petalorum rudimenta interdum praesentia)…” and is thus definite as to the presence or absence of petals. He further states in a footnote: “Zeitweises Verkommen von Kornblättern [Kronblättern] wurde irrig angegben von:… Tatsächlich habe ich weder in der Natur noch in den Herbarien biem europäischen Typus der Art je Kronblattrudimente finden können; die Angabe solcher beruht also wohl auf der Verwechslung mit anderen Arten oder auch darauf dass die Honigdrusen für rudimentäre Petalen angesehen wurden (diese werden oft als gelblich geschildert).” Our specimens do not match the description of var. intercedens Thell., so it would appear that L. ruderale Linn. as delimited by Thellung is probably absent from New Zealand. It can be noted that Thellung (1906: 135) queried the validity of Kirk's record of the species in The Student's Flora of New Zealand, stating, “Aus dem australisch-polynesischen Gebiet sah ich noch kein echtes L. ruderale; es ist aber nicht ausgeschlossen, dass sich die Pflanze dort eingeschleppt findet.” There are several distinct plants included in our concept of the species, one of which appears to be close to
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L. hyssopifolium Desv. Further collecting of plants of this complex is desirable, and will assist in the problem of clearing up the distribution of the various plants.
L. sativum Linn. Recorded by Hooker (1864: 15), the species is occasional; it has appeared in linen-flax crops sown with imported seed during the recent war period.
L. virginicum Linn. Recorded from Auckland and Whangarei by Allan (1940: 61), this species has been found in other localities: Edgecombe, Bay of Plenty, K. W. Allison 36685; Pongakawa Valley, Bay of Plenty, K. W. Allison 36691; Te Puke, 33777; Opotiki, N. Potts (?) 8310: 7780; Ongarue, King Country, 51049. The above specimens have the cotyledons accumbent, but there are a number of specimens from other localities with cotyledons oblique to incumbent, but identical with the above in all other respects, and which appear to belong to this species.
Sinapis dissecta Lag. This species has appeared in linen-flax crops, Invercargill, A. Stuart 45185.
Sisymbrium irio Linn. Recorded by Allan (1933: 38–39) from Auckland, the record is presumably based on specimens collected by H. Carse from a garden at Onehunga, Auckland, and represented by sheets numbered 5306, 5310 and 5311 in the herbarium of the Plant Research Bureau. These specimens are all S. orientale Linn., a species also recorded for the first time in the same paper by that author. It must be noted, however, that in the plate of drawings in Allan's paper, the representations of leaf and siliqua are correct for S. irio Linn., but they could obviously not have been made from the Auckland material, but were probably done from a specimen grown in New Zealand from Russian seed (15030). I have examined the Sisymbria in the main New Zealand herbaria, but have not seen any specimens of S. irio Linn., nor has it been noted in the field. Under these circumstances, I consider that this name should be removed from the naturalized flora.
S. orientale Linn. The distribution given by Allan (1933:39–40 and 1940: 65) is for the North Island only, and it has now been collected from several South Island localities: Seddon, Marlborough; Kaituna, Banks Peninsula; Templeton, G. Proudfoot; Lyttelton, H. H. Allan 45184; Rangitata Island; Timaru, R. Mason 33749, 33945, 33946.