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The highway to Kona leaves the Kilauea Military Camp through an open low Metrosideros wood with a conspicuous shrub layer of Styphelia and Dodonaea, and occasional yellow-green Santalum. On the right, after the Kipuka Puaulu Road Intersection, some Acacia koa saplings may be seen among the lehua. A public campground on the right is shaded by planted *Eucalyptus. Beyond this, good examples of kipukas may be seen an the hills to the right, "islands" of older surface and vegetation that were missed by the most recent lava flows. On a clear day the view of the broad rounded dome of Mauna Loa from here is superb, though its contour and the fact that the view is up a gradual slope makes it hard to realize that this is one of the really high mountains in the United States. Across the broad Keamoku Flow the lower slopes of Mauna Loa are grassy, with scattered trees.
About three miles from the camp the road enters the Keamoku Flow, an undated flow of rough dark aa lava with only scattered bushes. These include Styphelia, Metrosideros, Dodonaea and Vaccinium, with occasional Osteomeles. To the right is a steep grassy slope, probably an old fault scarp.
After about six miles down the gentle slope of the flow, the road leaves it and crosses some old pahoehoe lava, also with only scattered bushes, then open scrub lehua forest. About milepost 41 there are patches of lehua and of Dodonaea scrub, then rolling grasslands with scattered bushes on the slopes to the right. On the left is a mixture of Dodonaea scrub and lehua thicket. After some cultivated pastures there is some pahoehoe lava with irregular sparse scrub. The lehua trees are dead at the tops. In the distance on the right the slopes of Mauna Loa are covered by koa forest. The vegetation varies locally on old lava slopes, mostly pahoehoe. There are many planted trees, but large areas of them are dead or dying. The cause of this is not apparent. Opposite milepost 47 the lower slopes of Mauna Loa are densely forested. In the next two miles are cane fields on the slopes, also brushy pastures with scattered trees.
On old pahoehoe lava sparse scrub includes Dodonaea (aalii), Styphelia (pukeawe) and Metrosideros (lehua), with *Andropogon and other grasses. A good view of South Point may be had, ahead, between mileposts 49 and 50. *Lantana scrub, with some guava and *Schinus terebinthifolius, is seen in some of the pastures, that show evidence of very heavy grazing, there are windbreaks of Grevillea robusta, *Eucalyptus and *Casuarina, and scattered *Samanea saman (monkey pod) trees. Pahala, off the highway to the right, is a small town built around a sugar mill that serves the large Pahala Plantation, the fields of which have been visible on the slopes to the right.
The pastures here are somewhat brushy, with *Leucaena, *Samanea, and occasional *Prosopis, and with *Eugenia cumin) along watercourses. Then open grassland with very few trees extends down long gentle slopes toward the sea Locally there are *Agave sisalana, *Samanea, *Lantana camera and *Leucaena in the pastures. Near milepost 56 there is a patch of Aleurites moluccana (kukui), surrounded by *Leucaena scrub.
Beyond the road to Punaluu, which is on the coast, there are several old aa lava flows, with Leucaena-Lantana-Schinus scrub, and some *Opuntia. Canthium odoratum, a compact small tree or shrub with glossy leaves, becomes rather common. A fresh very rough aa flow with scattered small lehuas is followed by extensive old pahoehoe with low *Lantana scrub and scattered other shrubs. On the left are a few wind-sheared *Prosopis trees. After a mile or so, another fresh aa flow with widely scattered Myoporum sandwicensis (naio), some *Leucaena and *Pluchea odorata, then tussocky grassland with scattered *Prosopis.
After the Hutchinson sugar mill, the country is a mixture of grassland with scrub, some *Prosopis, then vast treeless grassy slopes, grazed by cattle. Around small ranch houses are planted trees. At Naalehu there are cane fields on the right, pasture on the left, then thickets of *Schinus with some guava forming a dense scrub, in places up to 4 m or more tall. At Waiohinu Village are coffee and orange trees. Then for some distance the hills are covered by *Schinus-Psidium thickets with, locally, trees of *Eugenia cumin). Between here and the Junction with the South Point Road are coffee plantations, planted *Eucalyptus, some small lehua trees, pastures, and much *Schinus terebinthifolius. Beyond the junction are pastures with scattered lehua trees and guava brush.
The 1868 flow is in places covered by fairly dense but low lehua, locally sparse; there is some bare open pahoehoe lava with a few depressed patches of Dubautia scabra,_ small lehua bushes, and tufts of Psilotum nudum. A stop here will permit examination of this lava surface. In cracks are Nephrolepis exaltata and Polypodium pellucidum. Vaccinium reticulatum is rare in rough places, Sadleria cyatheoides also. Styphelia tameimeiae reaches 2 m in height in sheltered places. Cladonia tufts are abundant and Rhacomitrium lanuginosum, a widespread gray moss, forms masses in deep crevices. Very locally in low spots is a little Cordyline fruticosa, with grass, *Pluchea, *Schinus, *Hypochaeris, and *Lactuca. Along the road is the strange endemic shrubby Rumex giganteus.
After this comes a somewhat older pahoehoe flow with larger lehua trees, then a still older one with grass. On an aa flow is open forest 3-5 m tall, of lehua, with some Myoporum and Styphelia scrub between the trees.
The 1887 aa flow is mainly a barren black clinker surface with a very few Sadleria and lehua, except in grassy kipukas. The 1907 aa flow has no plants except small small kipukas (islands of older surface not covered by the newer lava). An older, brown aa flow has scattered small gnarled lehua and a few Sophora chrysophylla, and a still older grassy pahoehoe surface has scattered lehua and an Aleurites (kukui) patch. Then there is a woodland of Sophora chrysophylla (mamani) and occasional Oracacna and Canthium. This Sophora belongs to section Edwardsia, characterized by winged pods. The other members of the section are scattered around the southern hemisphere. Between here and another tongue of the 1907 flow is taller open to almost closed lehua forest with: patches of mixed scrub. The 1907 flow here is bare except for conspicuous lichens _ereocaulon vulcan)) and small lehua and Sadleria here and there. On older aa lava beyond this are varied lehua forests, locally with a few other trees including mango and avocado.
At Manuka Park there will he a stop for lunch. The park is grassy, with many planted trees, both exotic and native, with labels giving the names. On the east side of the park is dense tall Metrosideros forest on very mossy aa lava. Although this is on the leeward side of the island, thus in the dry rain shadow, convection showers so modify the climate that truly mesophytic forest thrives. It is somewhat disturbed and influenced by the proximity of the park and highway, yet it still gives a good impression of the lehua forest as it responds to conditions of moderate-rainfall. A trail has been bulldozed into this forest for a short distance from the park, providing convenient access. The canopy layer is dominantly Metrosideros (lehua). The understory has a considerable assortment of native trees, with Osmanthus sandwicensis and Psychotria (Straussia) hawaiiensis perhaps the most common. A rather thin shrub layer is composed of several native species in addition to *Lantana camera, *Rubus rosaefolius, and *Psidium guajava. The ground cover, on the mossy rough lava, is not dense.
Along the beginning of the trail Peperomia reflexa and Peperomia sp., Cocculus cf. ferrandianus, and Nephrolepis exaltata may be seen on the ground, and Wikstroemia sp. among the *Lantana and guava shrubs. About 10 m in and just off the trail to the right is a slender Pittosporum hosmeri, notable for its enormous capsules. Somewhat farther in is the first Osmanthus and many small Psychotria, Pipturus cf. albidus (mamake), a few Cibotium cf. splendens, and a tall slender Reynoldsia sandwicensis (ohe makai). About 100 m or more from the edge of the forest, on the right of the trail, is a tree of Alphitonia ponderosa (kauila) with wood of such hardness and strength that the Hawaiians employed it where metals were used in other cultures. On the ground here *Drymaria cordata is abundant. Asplenium cf. caudatum is also growing on the rocks, with the creeping *Senecio mikanioides.
At the end of the trail Myrsine sp. and Canthium odoratum shrubs may be seen. Beyond the trail, up the slope, Psilotum nudum grows on the lava rocks. Pelea sp. is in the shrub layer and Alyxia olivaeformis (maile) climbs in the small trees. From here the route to be taken circles to the left through the thin undergrowth. Care should be taken as the lava makes rough walking. Those not feeling confident that they can walk on this ground may easily return along the bulldozed trail. In this forest X Antidesma kapuae is said to occur. Gouldia terminalis var. is occasional, as are Coprosma sp and Cibotium splendens.! Lycopodium phyllanthum is one of the few epiphytes in this wood. Phaius tankervilliae, Polypodium thunbergianum, Ophioglossum pendulum, Carex' sp. and Microlepia strigosa grow on the rough lava underfoot.
The transition from the aa lava onto deeply weathered soil is seen very conspicuously in the vegetation. The dense lehua forest gives way to guava scrub with a lower layer of *Rubus rosaefolius, and with an emergent stratum of widely spaced very tall lehua trees. Canthium odoratum, Wikstroemia sp., Cordyline!fr~ticosa, Osteomeles anthyllidifolia, and young Psychotria hawaiiensis are occasional in the scrub, with a few herbs, such as *Stachytarpheta dichotoma and Nephrolepis. This vegetation is more or less uniform above the park.
Leaving the park, the road passes through tall lehua forest similar to that just investigated, but near the road much choked with guava. Across a rough aa flow with sparse lehua, the vegetation changes to a dense guava brush with scattered tall slender lehua trees. The lehua forest becomes denser but is still tangled with tall guava and occasional small #Aleurites (kukui).
After about a mile of varying aspects of lehua forest and guava brush, there is a stone wall on the right and a grove of *Eugenia jambos (rose apple), then pasture invaded by guava. The famous Kona coffee plantations begin here. They are dependent upon the convection showers for their moisture and the cloudiness makes shading unnecessary. The coffee has a distinctive fine flavor.
The Hoopuloa Flow of 1926, which reached the sea and destroyed the village of Hoopuloa is rough aa, gray with the lichen Stereocaulon' and otherwise vegetated only by scattered small lehua and Nephrolepis.
Between this and the Aleka Flow of 1919 is a mosaic of patches of guava thicket, coffee plantation, lehua forest and *Schinus scrub, with scattered mango trees, kukui, abundant *Hedychium! along the road, and a *Casuarina grove.
The Aleka Flow is aa, similar to the Hoopuloa, but with more vegetation, especially small lehua. Between this and the next flow is mostly lehua forest, badly degraded and invaded by guava and *Schinus, occasional *Persea americana (avocado) and kukui, some pastures with abundant Nephrolepis. The Kapuna aa flow of 1950 is hare except for a few Nephrolepis near the road. A kipuka is visible up the slope to the right, also some lehua forest killed by the lava.
Beyond this is an irregular mosaic of farms, coffee plantations, thickets with guava' *Fourcraea, *Schinus, Pandanus, kukui, *Lantana scrub, *Ceiba pentandra (kapok) and mango trees. On the left, shortly before the Kaohe aa flow of 1950, Casaytha filiformis is noticeable both for its spectacular appearance and because it grows here at an unusual altitude. The narrow Kaohe Flow is bare except for Nephrolepis, as is the Honokua Flow' also 1950, a bit farther on. Between them are pastures, guava-kukni thickets, mango, *Samanea, and * *Grevillea trees, with *Plumeria rubra above the road just before the Honokua Flow.
From here to the Honaunau road thickets of guava and *Schinus predominate mixed with many other trees and shrubs, with pastures, farms, coffee plantations, and occasional patches of lehua forest. Cassytha is common along here, and *Albizia lebbek (woman's tongue), *Datura arborea (or U. dolichocarpa) and *Carica papaya may be seen.
The rest of the way to Kailua is through the coffee region of Kona. The coffee plantations form a belt above and below the road, mixed with pastures, patches of lehua forest, small farm houses and large mansions, all with great displays of ornamental plants. Along the road may be seen *Jacaranda acutifolia, *Spathodea campanulata, * *Macaranga grandifolia. Musa sapientum, *Sambucus mexicana, *Artocarpus altilis (breadfruit), in addition to trees mentioned above.
Descending toward Kailua the road crosses a dry belt, dominated by *Prosopis and *Pithecellobium, in which the town is situated.