@article {diane_transfer_2002, title = {Transfer cells in the seeds of Boraginales}, journal = {Bot. J. Linn. Soc.}, volume = {140}, number = {2}, year = {2002}, pages = {155{\textendash}164}, abstract = {

The presence of transfer cells (TCs) in the seeds of Boraginales (Boraginaceae s.s., Hydrophyllaceae, Heliotropiaceae, Ehretiaceae, Cordiaceae and Lennoaceae) has been reported but has not hitherto been studied systematically. This study, surveying the seed anatomy of 50 species of Boraginales, demonstrates that in Heliotropiaceae, Cordiaceae, Ehretiaceae and Lennoaceae, TCs are found in an uninterrupted course from the placenta via the funicle to the seed coat. These families are characterized by indehiscent fruits with a protective endocarp. The TCs may act as a sponge, thus promoting rapid germination when sufficient water is available. In Hydrophyllaceae, which have capsular fruits, TCs are often found but have a different structure and are restricted to the seed coat. Boraginaceae s.s. on the other hand are characterized by a complete absence of TCs in their seeds. The presence of TCs in seeds is considered as a synapomorphic trait and appears to be phylogenetically informative.

}, author = {Diane, N and Hilger, HH and Gottschling, M} } @article {hilger_untersuchungen_1982, title = {Untersuchungen zur Ausbildung der Klausen und ihrer Oberfl{\"a}chenskulpturen bei Paracaryum intermedium (Boraginaceae) aus Jordanien}, journal = {Beitr. Biol. Pflanzen}, volume = {57}, year = {1982}, pages = {205{\textendash}220}, author = {Hilger, HH and Richter, U} } @article {hilger_energiedispersive_1993, title = {Energiedispersive R{\"o}ntgenmikroanalyse (EDX) von Boraginaceae subfam. Boraginoideae - Klausenoberflachen. Sind Silicium- und Calcium - Einlagerungen in die Fruchtwand systematisch verwertbare Merkmale?}, journal = {Flora}, volume = {188}, year = {1993}, pages = {387{\textendash}398}, abstract = {

Energy dispersive X-ray microanalysis (EDX) was used to investigate surfaces of Boraginoideae nutlets with regard to their content and ratios of silicon (Si) and calcium (Ca), respectively. Deposition takes place very short prior to full maturity. Potassium (K) is a third always detectible element.
It is not possible to associate species to a tribe only with respect to different element contents. Morphology and sculpturing of nutlets play a more important role. The Lithospermeae which exhibit the most elaborate pericarp anatomy have a hight amount of Ca deposition in the lumina of the cells of the outermost mesocarp layer.

}, author = {Hilger, HH and Hoppe, JR and Hofmann, M} } @article {hilger_systematic_2003, title = {A systematic analysis of Heliotropiaceae (Boraginales) based on trnL and ITS1 sequence data}, journal = {Bot. Jahrb. Syst.}, volume = {125}, number = {1}, year = {2003}, pages = {19{\textendash}51}, abstract = {

The infrafamilial relationships of Heliotropiaceae (Boraginaceae subfam. Heliotropioideae according to traditional systems) are reevaluated using molecular data of nuclear ITS1 (86 species) and plastidal trn LUAA intron (66 species) sequences. The results obtained from our investigations show that traditional generic limits warrant adjustment. Heliotropiaceae fall into two large clades. The first clade includes, in basal position, the genus Ixorhea . The genus Myriopus (formerly Tournefortia sect. Cyphocyema) is sister to Euploca (formerly Hilgeria, Schleidenia, Heliotropium sect. Orthostachys). The remaining sections of Heliotropium, Tournefortia sect. Tournefortia and the three small genera Argusia, Ceballosia, and Nogalia, segregated from Heliotropium, constitute the second large clade. Argusia, Ceballosia, and Nogalia cluster within clades of Heliotropium and therefore are reincluded in this genus. Within Heliotropium, the species of former Tournefortia sect. Tournefortia represent a lineage of tropical New World Heliotropium species, growing in humid environments, whereas all other Heliotropium species are found in semi-arid habitats. Before new combinations in the genus Heliotropium are made for \"Tournefortia\", the exact relationship within New World Heliotropium needs to be resolved, and a revision of \"Tournefortia\" is inevitable. We advocate maintaining the genus Tournefortia, which is easily defined, and we conclude that under this definition the genus Heliotropium is paraphyletic. Five genera are thus accepted; 22 new combinations within Heliotropiaceae are presented.

}, author = {Hilger, HH and Diane, N} } @article {hilger_pontechium:_2000, title = {Pontechium: a new genus distinct from Echium and Lobostemon (Boraginaceae)}, journal = {Taxon}, volume = {49}, number = {4}, year = {2000}, pages = {737{\textendash}746}, abstract = {

Plastid (trnL(UAA) intron, trnL(UAA)-trnF(GAA) spacer) and nuclear (ITS1) DNA sequence analyses do not only confirm the separate position of \„Echium maculatum L.\" which this species holds within the genus Echium due to the presence of a bicapitate rather than a bifid stigma, but necessitate the exclusion of the taxon from the genus Echium (Boraginaceae) and the description of a new genus, Pontechium.

}, keywords = {{DNA}, Boraginaceae, Echiostachys, Echium, Lithospermeae, Lobostemon, Pontechium gen. nov.}, author = {Hilger, HH and B{\"o}hle, UR} }