Arceuthobium pollen is heterocolpate and echinate. The broad furrows
contain rough, irregular pores, and the short pseudocolpi contain fewer spines than
the intercopal area. Even there, the spines are much less dense than the Asteraceae,
for example. Some of the other genera in the Loranthaceae resemble Arceuthobium,
but most do not. The Loranthaceae is a eurypalynous family. Some of the European
Viscums have sparse sculpturing resembling spines or perhaps rods (bacculae),
and Viscum rotundifolium (right) exhibits pseudocolpi, but its sculpture
elements are different from those of Arceuthobium. The genus Antidaphne (above) has spines
similar to those of Arceuthobium but it lacks pseudocolpi.
The Loranthaceae are primarily tricolporate, but the examples below hint at
the tremendous variability of this family.
Small parasitic plants obtaining nutrition through haustoria, from host tissues.
Dwarf mistletoe plants are not in contact with the ground, and do not have roots. The plants
contain chlorophyll, but it is used for reproduction and water regulation rather
than as a source of energy for the parent plant. The host plants are conifers of the
Pinaceae and Cupressaceae. Only four species occur in the Europe and Asia, but
nearly 30 species occur in western and boreal North America.
Pollen light micrograph:
The sparsely-echinate grains are distinctly heterocolpate, with large furrows
alternating with short narrow ones.
Pollen scanning electron micrograph (SEM)
The same characteristics visible in light microscopy are apparent in SEM.
Production and Dispersal:
Both insect-pollinated and wind-pollinated species exist, with wind-pollinated taxa
more common in western North America (Baker et al., 1985). The production and dispersal
are low, even for the wind-pollinated species however, so percentages are never high. And,
the presence of Arceuthobium in fossil samples is a good indication of nearby
occurrence of the plants - and of conifers.
The pollen wall is thin, and the grains probably do not preserve well.
Arceuthobium-like pollen (Spinulaepollis) has been identified
from the Eocene through Pliocene of Germany (Krutzch, 1962). Leopold (Hawksworth
and Wiens, 1972) has identified Arceuthobium pollen from Miocene and
younger sediments of North America.
- Baird, J. R. 1968.
A Taxonomic Revision of the Plant Family Arceuthobium of North America, North of Mexico.
Ph.D. thesis. University of North Carolina.
- Baker, F.A., French, D.W., Kulmann, H.M., Davis, O.K., and Bright, R.C. 1985.
Pollination of the eastern dwarf mistletoe. Canadian Journal of Forest Research 15:708 714.
- Chevalier, A. 1901.
Monographie des Myricacées. Mém. Soc. Sci. Nat. Cherbourg 32: 85-340.
- Elias, T. S. 1971. The genera of Arceuthobium in the southeastern United States.
J. Arnold Arbor. 52: 305-318.
- Feuer, S., and Kuijt. J. 1978. Fine structure of mistletoe pollen.
Eremolepidaceae, Lepidoceras and Tupeia. Can. J. Bot. 56: 2853-2864.
- Feuer, S., and Kuijt, J. 1979. Fine structure of mistletoe pollen. II.
Pollen morphology and evolution in the genus Psittacanthus Mart. (Loranthaceae).
Bot. Not. 132: 295-309.
- Feuer, S., and Kuijt, J. 1980. Fine structure of mistletoe pollen. III. Large-flowered
neotropical Loranthaceae and their Australian relatives. Amer. J. Bot. 67: 34-50.
- Feuer, S., and Kuijt, J. 1982. Fine structure of mistletoe pollen, IV.
Eurasian and Australian Viscum L. (Viscaceae). Amer. J. Bot. 69: 1-12.
- Feuer, S., Kuijt, J., and Wiens, D. 1982. Fine structure of mistletoe pollen, V.
Madagascan and continental African Viscum L. (Viscaceae).
Amer. J. Bot. 69: 163-187.
- Feuer, S., and Kuijt, J. 1985. Fine structure of mistletoe pollen. VI.
Small-flowered neotropical Loranthaceae. Ann. Missouri Bot. Gard. 72: 187-212
- Hawksworth, F. G. and Wiens, D. 1972. Biology and classification of dwarf mistletoes
(Arceuthobium) USDA Forest Service Agriculture Handbook no. 401.
- Krutzch, W. von. 1962. Stratigraphische bzw. botanisch wichtige neue Sporene und Pollenformene
aus dem deutschen Tertiar. Geologie 11: 265-319.
- Sheffy, M. V. 1972.
A Study of the Arceuthobium from Eocene Sediments of Southeastern North America.
Ph.D. thesis. Indiana University.
- Wilbur, R. L. 1994. The Arceuthobium of the United States and Canada:
Genera, subgenera, and series. Sida 16(1): 93-107.
- Youngken, H. W. 1919. The comparative morphology,
taxonomy and distribution of the Arceuthobium of the eastern United States.
Contr. Bot. Lab. Morris Arbor. Univ. Pennsylvania 4: 339-400.